Struct TextOpacity 

pub struct TextOpacity(pub u8);

A metadata field for TextDisplay.

Tuple Fields

0: u8

Methods from Deref<Target = u8>

pub fn count_ones(self) -> u32

Returns the number of ones in the binary representation of self.

Examples

let n = 0b01001100u8;
assert_eq!(n.count_ones(), 3);

let max = u8::MAX;
assert_eq!(max.count_ones(), 8);

let zero = 0u8;
assert_eq!(zero.count_ones(), 0);

pub fn count_zeros(self) -> u32

Returns the number of zeros in the binary representation of self.

Examples

let zero = 0u8;
assert_eq!(zero.count_zeros(), 8);

let max = u8::MAX;
assert_eq!(max.count_zeros(), 0);

This is heavily dependent on the width of the type, and thus might give surprising results depending on type inference:

let lucky = 7;
foo(lucky);
assert_eq!(lucky.count_zeros(), 5);
assert_eq!(lucky.count_ones(), 3);

let lucky = 7;
bar(lucky);
assert_eq!(lucky.count_zeros(), 13);
assert_eq!(lucky.count_ones(), 3);

You might want to use Self::count_ones instead, or emphasize the type you’re using in the call rather than method syntax:

let small = 1;
assert_eq!(u8::count_zeros(small), 7);

pub fn leading_zeros(self) -> u32

Returns the number of leading zeros in the binary representation of self.

Depending on what you’re doing with the value, you might also be interested in the ilog2 function which returns a consistent number, even if the type widens.

Examples

let n = u8::MAX >> 2;
assert_eq!(n.leading_zeros(), 2);

let zero = 0u8;
assert_eq!(zero.leading_zeros(), 8);

let max = u8::MAX;
assert_eq!(max.leading_zeros(), 0);

pub fn trailing_zeros(self) -> u32

Returns the number of trailing zeros in the binary representation of self.

Examples

let n = 0b0101000u8;
assert_eq!(n.trailing_zeros(), 3);

let zero = 0u8;
assert_eq!(zero.trailing_zeros(), 8);

let max = u8::MAX;
assert_eq!(max.trailing_zeros(), 0);

pub fn leading_ones(self) -> u32

Returns the number of leading ones in the binary representation of self.

Examples

let n = !(u8::MAX >> 2);
assert_eq!(n.leading_ones(), 2);

let zero = 0u8;
assert_eq!(zero.leading_ones(), 0);

let max = u8::MAX;
assert_eq!(max.leading_ones(), 8);

pub fn trailing_ones(self) -> u32

Returns the number of trailing ones in the binary representation of self.

Examples

let n = 0b1010111u8;
assert_eq!(n.trailing_ones(), 3);

let zero = 0u8;
assert_eq!(zero.trailing_ones(), 0);

let max = u8::MAX;
assert_eq!(max.trailing_ones(), 8);

pub fn bit_width(self) -> u32

Returns the minimum number of bits required to represent self.

This method returns zero if self is zero.

Examples

assert_eq!(0_u8.bit_width(), 0);
assert_eq!(0b111_u8.bit_width(), 3);
assert_eq!(0b1110_u8.bit_width(), 4);
assert_eq!(u8::MAX.bit_width(), 8);

pub fn isolate_highest_one(self) -> u8

Returns self with only the most significant bit set, or 0 if the input is 0.

Examples

let n: u8 = 0b_01100100;

assert_eq!(n.isolate_highest_one(), 0b_01000000);
assert_eq!(0_u8.isolate_highest_one(), 0);

pub fn isolate_lowest_one(self) -> u8

Returns self with only the least significant bit set, or 0 if the input is 0.

Examples

let n: u8 = 0b_01100100;

assert_eq!(n.isolate_lowest_one(), 0b_00000100);
assert_eq!(0_u8.isolate_lowest_one(), 0);

pub fn highest_one(self) -> Option<u32>

Returns the index of the highest bit set to one in self, or None if self is 0.

Note that this is equivalent to checked_ilog2.

Examples

assert_eq!(0b0_u8.highest_one(), None);
assert_eq!(0b1_u8.highest_one(), Some(0));
assert_eq!(0b1_0000_u8.highest_one(), Some(4));
assert_eq!(0b1_1111_u8.highest_one(), Some(4));

pub fn lowest_one(self) -> Option<u32>

Returns the index of the lowest bit set to one in self, or None if self is 0.

Examples

assert_eq!(0b0_u8.lowest_one(), None);
assert_eq!(0b1_u8.lowest_one(), Some(0));
assert_eq!(0b1_0000_u8.lowest_one(), Some(4));
assert_eq!(0b1_1111_u8.lowest_one(), Some(0));

pub fn cast_signed(self) -> i8

Returns the bit pattern of self reinterpreted as a signed integer of the same size.

This produces the same result as an as cast, but ensures that the bit-width remains the same.

Examples

let n = u8::MAX;

assert_eq!(n.cast_signed(), -1i8);

pub fn saturating_cast_signed(self) -> i8

🔬This is a nightly-only experimental API. (integer_cast_extras)

Saturating conversion of self to a signed integer of the same size.

The signed integer’s maximum value is returned if self is larger than the maximum positive value representable by the signed integer.

For other kinds of signed integer casts, see cast_signed, checked_cast_signed, or strict_cast_signed.

Examples

#![feature(integer_cast_extras)]
let n = u8::MAX;

assert_eq!(n.saturating_cast_signed(), i8::MAX);
assert_eq!(64u8.saturating_cast_signed(), 64i8);

pub fn checked_cast_signed(self) -> Option<i8>

🔬This is a nightly-only experimental API. (integer_cast_extras)

Checked conversion of self to a signed integer of the same size, returning None if self is larger than the signed integer’s maximum value.

For other kinds of signed integer casts, see cast_signed, saturating_cast_signed, or strict_cast_signed.

Examples

#![feature(integer_cast_extras)]
let n = u8::MAX;

assert_eq!(n.checked_cast_signed(), None);
assert_eq!(64u8.checked_cast_signed(), Some(64i8));

pub fn strict_cast_signed(self) -> i8

🔬This is a nightly-only experimental API. (integer_cast_extras)

Strict conversion of self to a signed integer of the same size, which panics if self is larger than the signed integer’s maximum value.

For other kinds of signed integer casts, see cast_signed, checked_cast_signed, or saturating_cast_signed.

Examples

#![feature(integer_cast_extras)]
let _ = u8::MAX.strict_cast_signed();

pub fn rotate_left(self, n: u32) -> u8

Shifts the bits to the left by a specified amount, n, wrapping the truncated bits to the end of the resulting integer.

rotate_left(n) is equivalent to applying rotate_left(1) a total of n times. In particular, a rotation by the number of bits in self returns the input value unchanged.

Please note this isn’t the same operation as the << shifting operator!

Examples

let n = 0x82u8;
let m = 0x0a;

assert_eq!(n.rotate_left(2), m);
assert_eq!(n.rotate_left(1024), n);

pub fn rotate_right(self, n: u32) -> u8

Shifts the bits to the right by a specified amount, n, wrapping the truncated bits to the beginning of the resulting integer.

rotate_right(n) is equivalent to applying rotate_right(1) a total of n times. In particular, a rotation by the number of bits in self returns the input value unchanged.

Please note this isn’t the same operation as the >> shifting operator!

Examples

let n = 0x0au8;
let m = 0x82;

assert_eq!(n.rotate_right(2), m);
assert_eq!(n.rotate_right(1024), n);

pub fn funnel_shl(self, right: u8, n: u32) -> u8

Performs a left funnel shift.

This operation can be thought of as concatenating self and right into an integer twice the size of u8, performing a left shift by n, and returning the left half of the result.

The name comes from “funneling” a wider integer to a narrower integer.

Panics

Overflow behavior

If overflow checks are enabled (default in debug mode), this function will panic if n is greater than or equal to the number of bits in self. If overflow checks are disabled (default in release mode), there is no panic; instead, the value is shifted by n % Self::BITS.

Examples

let a = 0x82_u8;
let b = 0x36_u8;

assert_eq!(a.funnel_shl(b, 2), 0x08);

// Using zeros as the right operand acts as a normal shift left
assert_eq!(a.funnel_shl(0, 2), a << 2);

// Shifting by 0 returns `self` unchanged
assert_eq!(a.funnel_shl(b, 0), a);

// Using the same value as the right operand acts as a rotate
assert_eq!(a.funnel_shl(a, 2), a.rotate_left(2));

Note that while funnel_shl can act as a rotate, it does not allow for rotating by an unbounded amount like rotate_left does:

let a = u8::MAX;
// Okay
let _ = a.rotate_left(u8::BITS);
// Panics (only when overflow checks are enabled)
let _ = a.funnel_shl(a, u8::BITS);

pub fn funnel_shr(self, right: u8, n: u32) -> u8

Performs a right funnel shift.

This operation can be thought of as concatenating self and right into an integer twice the size of u8, performing a right shift by n, and returning the right half of the result.

The name comes from “funneling” a wider integer to a narrower integer.

Panics

Overflow behavior

If overflow checks are enabled (default in debug mode), this function will panic if n is greater than or equal to the number of bits in self. If overflow checks are disabled (default in release mode), there is no panic; instead, the value is shifted by n % Self::BITS.

Examples

let a = 0x82_u8;
let b = 0x36_u8;

assert_eq!(a.funnel_shr(b, 2), 0x8d);

// Using zeros as the left operand acts as a normal shift right
assert_eq!(0_u8.funnel_shr(a, 2), a >> 2);

// Shifting by 0 returns `right` unchanged
assert_eq!(b.funnel_shr(a, 0), a);

// Using the same value as the right operand acts as a rotate
assert_eq!(a.funnel_shr(a, 2), a.rotate_right(2));

Note that while funnel_shr can act as a rotate, it does not allow for rotating by an unbounded amount like rotate_right does:

let a = u8::MAX;
// Okay
let _ = a.rotate_right(u8::BITS);
// Panics (only when overflow checks are enabled)
let _ = a.funnel_shr(a, u8::BITS);

pub unsafe fn unchecked_funnel_shl(self, right: u8, n: u32) -> u8

Unchecked funnel shift left.

Safety

This results in undefined behavior if n is greater than or equal to u8::BITS, i.e. when funnel_shl would panic.

pub unsafe fn unchecked_funnel_shr(self, right: u8, n: u32) -> u8

Unchecked funnel shift right.

Safety

This results in undefined behavior if n is greater than or equal to u8::BITS, i.e. when funnel_shr would panic.

pub fn carryless_mul(self, rhs: u8) -> u8

🔬This is a nightly-only experimental API. (uint_carryless_mul)

Performs a carry-less multiplication, returning the lower bits.

This operation is similar to long multiplication in base 2, except that exclusive or is used instead of addition. The implementation is equivalent to:

pub fn carryless_mul(lhs: u8, rhs: u8) -> u8{
    let mut retval = 0;
    for i in 0..u8::BITS {
        if (rhs >> i) & 1 != 0 {
            // long multiplication would use +=
            retval ^= lhs << i;
        }
    }
    retval
}

The actual implementation is more efficient, and on some platforms lowers directly to a dedicated instruction.

Uses

Carryless multiplication can be used to turn a bitmask of quote characters into a bit mask of characters surrounded by quotes:

r#"abc xxx "foobar" zzz "a"!"#; // input string
 0b0000000010000001000001010; // quote_mask
 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask

Another use is in cryptography, where carryless multiplication allows for efficient implementations of polynomial multiplication in GF(2)[X], the polynomial ring over GF(2).

Examples

#![feature(uint_carryless_mul)]

let a = 0x12u8;
let b = 0x34u8;

assert_eq!(a.carryless_mul(b), 0x28);

pub fn swap_bytes(self) -> u8

Reverses the byte order of the integer.

Examples

let n = 0x12u8;
let m = n.swap_bytes();

assert_eq!(m, 0x12);

pub fn extract_bits(self, mask: u8) -> u8

🔬This is a nightly-only experimental API. (uint_gather_scatter_bits)

Returns an integer with the bit locations specified by mask packed contiguously into the least significant bits of the result.

#![feature(uint_gather_scatter_bits)]
let n: u8 = 0b1011_1100;

assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
assert_eq!(n.extract_bits(0xF0), 0b0000_1011);

pub fn deposit_bits(self, mask: u8) -> u8

🔬This is a nightly-only experimental API. (uint_gather_scatter_bits)

Returns an integer with the least significant bits of self distributed to the bit locations specified by mask.

#![feature(uint_gather_scatter_bits)]
let n: u8 = 0b1010_1101;

assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);

pub fn reverse_bits(self) -> u8

Reverses the order of bits in the integer. The least significant bit becomes the most significant bit, second least-significant bit becomes second most-significant bit, etc.

Examples

let n = 0x12u8;
let m = n.reverse_bits();

assert_eq!(m, 0x48);
assert_eq!(0, 0u8.reverse_bits());

pub fn to_be(self) -> u8

Converts self to big endian from the target’s endianness.

On big endian this is a no-op. On little endian the bytes are swapped.

Examples

let n = 0x1Au8;

if cfg!(target_endian = "big") {
    assert_eq!(n.to_be(), n)
} else {
    assert_eq!(n.to_be(), n.swap_bytes())
}

pub fn to_le(self) -> u8

Converts self to little endian from the target’s endianness.

On little endian this is a no-op. On big endian the bytes are swapped.

Examples

let n = 0x1Au8;

if cfg!(target_endian = "little") {
    assert_eq!(n.to_le(), n)
} else {
    assert_eq!(n.to_le(), n.swap_bytes())
}

pub fn checked_add(self, rhs: u8) -> Option<u8>

Checked integer addition. Computes self + rhs, returning None if overflow occurred.

Examples

assert_eq!((u8::MAX - 2).checked_add(1), Some(u8::MAX - 1));
assert_eq!((u8::MAX - 2).checked_add(3), None);

pub fn strict_add(self, rhs: u8) -> u8

Strict integer addition. Computes self + rhs, panicking if overflow occurred.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!((u8::MAX - 2).strict_add(1), u8::MAX - 1);

The following panics because of overflow:

let _ = (u8::MAX - 2).strict_add(3);

pub unsafe fn unchecked_add(self, rhs: u8) -> u8

Unchecked integer addition. Computes self + rhs, assuming overflow cannot occur.

Calling x.unchecked_add(y) is semantically equivalent to calling x.checked_add(y).unwrap_unchecked().

If you’re just trying to avoid the panic in debug mode, then do not use this. Instead, you’re looking for wrapping_add.

Safety

This results in undefined behavior when self + rhs > u8::MAX, i.e. when checked_add would return None.

pub fn checked_add_signed(self, rhs: i8) -> Option<u8>

Checked addition with a signed integer. Computes self + rhs, returning None if overflow occurred.

Examples

assert_eq!(1u8.checked_add_signed(2), Some(3));
assert_eq!(1u8.checked_add_signed(-2), None);
assert_eq!((u8::MAX - 2).checked_add_signed(3), None);

pub fn strict_add_signed(self, rhs: i8) -> u8

Strict addition with a signed integer. Computes self + rhs, panicking if overflow occurred.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(1u8.strict_add_signed(2), 3);

The following panic because of overflow:

let _ = 1u8.strict_add_signed(-2);

let _ = (u8::MAX - 2).strict_add_signed(3);

pub fn checked_sub(self, rhs: u8) -> Option<u8>

Checked integer subtraction. Computes self - rhs, returning None if overflow occurred.

Examples

assert_eq!(1u8.checked_sub(1), Some(0));
assert_eq!(0u8.checked_sub(1), None);

pub fn strict_sub(self, rhs: u8) -> u8

Strict integer subtraction. Computes self - rhs, panicking if overflow occurred.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(1u8.strict_sub(1), 0);

The following panics because of overflow:

let _ = 0u8.strict_sub(1);

pub unsafe fn unchecked_sub(self, rhs: u8) -> u8

Unchecked integer subtraction. Computes self - rhs, assuming overflow cannot occur.

Calling x.unchecked_sub(y) is semantically equivalent to calling x.checked_sub(y).unwrap_unchecked().

If you’re just trying to avoid the panic in debug mode, then do not use this. Instead, you’re looking for wrapping_sub.

If you find yourself writing code like this:

if foo >= bar {
    // SAFETY: just checked it will not overflow
    let diff = unsafe { foo.unchecked_sub(bar) };
    // ... use diff ...
}

Consider changing it to

if let Some(diff) = foo.checked_sub(bar) {
    // ... use diff ...
}

As that does exactly the same thing – including telling the optimizer that the subtraction cannot overflow – but avoids needing unsafe.

Safety

This results in undefined behavior when self - rhs < u8::MIN, i.e. when checked_sub would return None.

pub fn checked_sub_signed(self, rhs: i8) -> Option<u8>

Checked subtraction with a signed integer. Computes self - rhs, returning None if overflow occurred.

Examples

assert_eq!(1u8.checked_sub_signed(2), None);
assert_eq!(1u8.checked_sub_signed(-2), Some(3));
assert_eq!((u8::MAX - 2).checked_sub_signed(-4), None);

pub fn strict_sub_signed(self, rhs: i8) -> u8

Strict subtraction with a signed integer. Computes self - rhs, panicking if overflow occurred.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(3u8.strict_sub_signed(2), 1);

The following panic because of overflow:

let _ = 1u8.strict_sub_signed(2);

let _ = (u8::MAX).strict_sub_signed(-1);

pub fn checked_signed_diff(self, rhs: u8) -> Option<i8>

Checked integer subtraction. Computes self - rhs and checks if the result fits into an i8, returning None if overflow occurred.

Examples

assert_eq!(10u8.checked_signed_diff(2), Some(8));
assert_eq!(2u8.checked_signed_diff(10), Some(-8));
assert_eq!(u8::MAX.checked_signed_diff(i8::MAX as u8), None);
assert_eq!((i8::MAX as u8).checked_signed_diff(u8::MAX), Some(i8::MIN));
assert_eq!((i8::MAX as u8 + 1).checked_signed_diff(0), None);
assert_eq!(u8::MAX.checked_signed_diff(u8::MAX), Some(0));

pub fn checked_mul(self, rhs: u8) -> Option<u8>

Checked integer multiplication. Computes self * rhs, returning None if overflow occurred.

Examples

assert_eq!(5u8.checked_mul(1), Some(5));
assert_eq!(u8::MAX.checked_mul(2), None);

pub fn strict_mul(self, rhs: u8) -> u8

Strict integer multiplication. Computes self * rhs, panicking if overflow occurred.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(5u8.strict_mul(1), 5);

The following panics because of overflow:

let _ = u8::MAX.strict_mul(2);

pub unsafe fn unchecked_mul(self, rhs: u8) -> u8

Unchecked integer multiplication. Computes self * rhs, assuming overflow cannot occur.

Calling x.unchecked_mul(y) is semantically equivalent to calling x.checked_mul(y).unwrap_unchecked().

If you’re just trying to avoid the panic in debug mode, then do not use this. Instead, you’re looking for wrapping_mul.

Safety

This results in undefined behavior when self * rhs > u8::MAX, i.e. when checked_mul would return None.

pub fn checked_div(self, rhs: u8) -> Option<u8>

Checked integer division. Computes self / rhs, returning None if rhs == 0.

Examples

assert_eq!(128u8.checked_div(2), Some(64));
assert_eq!(1u8.checked_div(0), None);

pub fn strict_div(self, rhs: u8) -> u8

Strict integer division. Computes self / rhs.

Strict division on unsigned types is just normal division. There’s no way overflow could ever happen. This function exists so that all operations are accounted for in the strict operations.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.strict_div(10), 10);

The following panics because of division by zero:

let _ = (1u8).strict_div(0);

pub fn checked_div_euclid(self, rhs: u8) -> Option<u8>

Checked Euclidean division. Computes self.div_euclid(rhs), returning None if rhs == 0.

Examples

assert_eq!(128u8.checked_div_euclid(2), Some(64));
assert_eq!(1u8.checked_div_euclid(0), None);

pub fn strict_div_euclid(self, rhs: u8) -> u8

Strict Euclidean division. Computes self.div_euclid(rhs).

Strict division on unsigned types is just normal division. There’s no way overflow could ever happen. This function exists so that all operations are accounted for in the strict operations. Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self.strict_div(rhs).

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.strict_div_euclid(10), 10);

The following panics because of division by zero:

let _ = (1u8).strict_div_euclid(0);

pub fn checked_div_exact(self, rhs: u8) -> Option<u8>

🔬This is a nightly-only experimental API. (exact_div)

Checked integer division without remainder. Computes self / rhs, returning None if rhs == 0 or if self % rhs != 0.

Examples

#![feature(exact_div)]
assert_eq!(64u8.checked_div_exact(2), Some(32));
assert_eq!(64u8.checked_div_exact(32), Some(2));
assert_eq!(64u8.checked_div_exact(0), None);
assert_eq!(65u8.checked_div_exact(2), None);

pub fn div_exact(self, rhs: u8) -> Option<u8>

🔬This is a nightly-only experimental API. (exact_div)

Integer division without remainder. Computes self / rhs, returning None if self % rhs != 0.

Panics

This function will panic if rhs == 0.

Examples

#![feature(exact_div)]
assert_eq!(64u8.div_exact(2), Some(32));
assert_eq!(64u8.div_exact(32), Some(2));
assert_eq!(65u8.div_exact(2), None);

pub unsafe fn unchecked_div_exact(self, rhs: u8) -> u8

🔬This is a nightly-only experimental API. (exact_div)

Unchecked integer division without remainder. Computes self / rhs.

Safety

This results in undefined behavior when rhs == 0 or self % rhs != 0, i.e. when checked_div_exact would return None.

pub fn checked_rem(self, rhs: u8) -> Option<u8>

Checked integer remainder. Computes self % rhs, returning None if rhs == 0.

Examples

assert_eq!(5u8.checked_rem(2), Some(1));
assert_eq!(5u8.checked_rem(0), None);

pub fn strict_rem(self, rhs: u8) -> u8

Strict integer remainder. Computes self % rhs.

Strict remainder calculation on unsigned types is just the regular remainder calculation. There’s no way overflow could ever happen. This function exists so that all operations are accounted for in the strict operations.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.strict_rem(10), 0);

The following panics because of division by zero:

let _ = 5u8.strict_rem(0);

pub fn checked_rem_euclid(self, rhs: u8) -> Option<u8>

Checked Euclidean modulo. Computes self.rem_euclid(rhs), returning None if rhs == 0.

Examples

assert_eq!(5u8.checked_rem_euclid(2), Some(1));
assert_eq!(5u8.checked_rem_euclid(0), None);

pub fn strict_rem_euclid(self, rhs: u8) -> u8

Strict Euclidean modulo. Computes self.rem_euclid(rhs).

Strict modulo calculation on unsigned types is just the regular remainder calculation. There’s no way overflow could ever happen. This function exists so that all operations are accounted for in the strict operations. Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self.strict_rem(rhs).

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.strict_rem_euclid(10), 0);

The following panics because of division by zero:

let _ = 5u8.strict_rem_euclid(0);

pub unsafe fn unchecked_disjoint_bitor(self, other: u8) -> u8

🔬This is a nightly-only experimental API. (disjoint_bitor)

Same value as self | other, but UB if any bit position is set in both inputs.

This is a situational micro-optimization for places where you’d rather use addition on some platforms and bitwise or on other platforms, based on exactly which instructions combine better with whatever else you’re doing. Note that there’s no reason to bother using this for places where it’s clear from the operations involved that they can’t overlap. For example, if you’re combining u16s into a u32 with ((a as u32) << 16) | (b as u32), that’s fine, as the backend will know those sides of the | are disjoint without needing help.

Examples

#![feature(disjoint_bitor)]

// SAFETY: `1` and `4` have no bits in common.
unsafe {
    assert_eq!(1_u8.unchecked_disjoint_bitor(4), 5);
}

Safety

Requires that (self & other) == 0, otherwise it’s immediate UB.

Equivalently, requires that (self | other) == (self + other).

pub fn ilog(self, base: u8) -> u32

Returns the logarithm of the number with respect to an arbitrary base, rounded down.

This method might not be optimized owing to implementation details; ilog2 can produce results more efficiently for base 2, and ilog10 can produce results more efficiently for base 10.

Panics

This function will panic if self is zero, or if base is less than 2.

Examples

assert_eq!(5u8.ilog(5), 1);

pub fn ilog2(self) -> u32

Returns the base 2 logarithm of the number, rounded down.

Panics

This function will panic if self is zero.

Examples

assert_eq!(2u8.ilog2(), 1);

pub fn ilog10(self) -> u32

Returns the base 10 logarithm of the number, rounded down.

Panics

This function will panic if self is zero.

Example

assert_eq!(10u8.ilog10(), 1);

pub fn checked_ilog(self, base: u8) -> Option<u32>

Returns the logarithm of the number with respect to an arbitrary base, rounded down.

Returns None if the number is zero, or if the base is not at least 2.

This method might not be optimized owing to implementation details; checked_ilog2 can produce results more efficiently for base 2, and checked_ilog10 can produce results more efficiently for base 10.

Examples

assert_eq!(5u8.checked_ilog(5), Some(1));
assert_eq!(4u8.checked_ilog(5), Some(0));
assert_eq!(5u8.checked_ilog(0), None);
assert_eq!(5u8.checked_ilog(1), None);
assert_eq!(0u8.checked_ilog(1), None);

pub fn checked_ilog2(self) -> Option<u32>

Returns the base 2 logarithm of the number, rounded down.

Returns None if the number is zero.

Note that this is equivalent to highest_one.

Examples

assert_eq!(2u8.checked_ilog2(), Some(1));

pub fn checked_ilog10(self) -> Option<u32>

Returns the base 10 logarithm of the number, rounded down.

Returns None if the number is zero.

Examples

assert_eq!(10u8.checked_ilog10(), Some(1));

pub fn checked_neg(self) -> Option<u8>

Checked negation. Computes -self, returning None unless self == 0.

Note that negating any positive integer will overflow.

Examples

assert_eq!(0u8.checked_neg(), Some(0));
assert_eq!(1u8.checked_neg(), None);

pub fn strict_neg(self) -> u8

Strict negation. Computes -self, panicking unless self == 0.

Note that negating any positive integer will overflow.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(0u8.strict_neg(), 0);

The following panics because of overflow:

let _ = 1u8.strict_neg();

pub fn checked_shl(self, rhs: u32) -> Option<u8>

Checked shift left. Computes self << rhs, returning None if rhs is larger than or equal to the number of bits in self.

Examples

assert_eq!(0x1u8.checked_shl(4), Some(0x10));
assert_eq!(0x10u8.checked_shl(129), None);
assert_eq!(0x10u8.checked_shl(7), Some(0));

pub fn strict_shl(self, rhs: u32) -> u8

Strict shift left. Computes self << rhs, panicking if rhs is larger than or equal to the number of bits in self.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(0x1u8.strict_shl(4), 0x10);

The following panics because of overflow:

let _ = 0x10u8.strict_shl(129);

pub unsafe fn unchecked_shl(self, rhs: u32) -> u8

Unchecked shift left. Computes self << rhs, assuming that rhs is less than the number of bits in self.

Safety

This results in undefined behavior if rhs is larger than or equal to the number of bits in self, i.e. when checked_shl would return None.

pub fn unbounded_shl(self, rhs: u32) -> u8

Unbounded shift left. Computes self << rhs, without bounding the value of rhs.

If rhs is larger or equal to the number of bits in self, the entire value is shifted out, and 0 is returned.

Examples

assert_eq!(0x1_u8.unbounded_shl(4), 0x10);
assert_eq!(0x1_u8.unbounded_shl(129), 0);
assert_eq!(0b101_u8.unbounded_shl(0), 0b101);
assert_eq!(0b101_u8.unbounded_shl(1), 0b1010);
assert_eq!(0b101_u8.unbounded_shl(2), 0b10100);
assert_eq!(42_u8.unbounded_shl(8), 0);
assert_eq!(42_u8.unbounded_shl(1).unbounded_shl(7), 0);

let start : u8 = 13;
let mut running = start;
for i in 0..160 {
    // The unbounded shift left by i is the same as `<< 1` i times
    assert_eq!(running, start.unbounded_shl(i));
    // Which is not always the case for a wrapping shift
    assert_eq!(running == start.wrapping_shl(i), i < 8);

    running <<= 1;
}

pub fn shl_exact(self, rhs: u32) -> Option<u8>

🔬This is a nightly-only experimental API. (exact_bitshifts)

Exact shift left. Computes self << rhs as long as it can be reversed losslessly.

Returns None if any non-zero bits would be shifted out or if rhs >= u8::BITS. Otherwise, returns Some(self << rhs).

Examples

#![feature(exact_bitshifts)]

assert_eq!(0x1u8.shl_exact(4), Some(0x10));
assert_eq!(0x1u8.shl_exact(129), None);

pub unsafe fn unchecked_shl_exact(self, rhs: u32) -> u8

🔬This is a nightly-only experimental API. (exact_bitshifts)

Unchecked exact shift left. Computes self << rhs, assuming the operation can be losslessly reversed rhs cannot be larger than u8::BITS.

Safety

This results in undefined behavior when rhs > self.leading_zeros() || rhs >= u8::BITS i.e. when u8::shl_exact would return None.

pub fn checked_shr(self, rhs: u32) -> Option<u8>

Checked shift right. Computes self >> rhs, returning None if rhs is larger than or equal to the number of bits in self.

Examples

assert_eq!(0x10u8.checked_shr(4), Some(0x1));
assert_eq!(0x10u8.checked_shr(129), None);

pub fn strict_shr(self, rhs: u32) -> u8

Strict shift right. Computes self >> rhs, panicking if rhs is larger than or equal to the number of bits in self.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(0x10u8.strict_shr(4), 0x1);

The following panics because of overflow:

let _ = 0x10u8.strict_shr(129);

pub unsafe fn unchecked_shr(self, rhs: u32) -> u8

Unchecked shift right. Computes self >> rhs, assuming that rhs is less than the number of bits in self.

Safety

This results in undefined behavior if rhs is larger than or equal to the number of bits in self, i.e. when checked_shr would return None.

pub fn unbounded_shr(self, rhs: u32) -> u8

Unbounded shift right. Computes self >> rhs, without bounding the value of rhs.

If rhs is larger or equal to the number of bits in self, the entire value is shifted out, and 0 is returned.

Examples

assert_eq!(0x10_u8.unbounded_shr(4), 0x1);
assert_eq!(0x10_u8.unbounded_shr(129), 0);
assert_eq!(0b1010_u8.unbounded_shr(0), 0b1010);
assert_eq!(0b1010_u8.unbounded_shr(1), 0b101);
assert_eq!(0b1010_u8.unbounded_shr(2), 0b10);
assert_eq!(42_u8.unbounded_shr(8), 0);
assert_eq!(42_u8.unbounded_shr(1).unbounded_shr(7), 0);

let start = u8::rotate_right(13, 4);
let mut running = start;
for i in 0..160 {
    // The unbounded shift right by i is the same as `>> 1` i times
    assert_eq!(running, start.unbounded_shr(i));
    // Which is not always the case for a wrapping shift
    assert_eq!(running == start.wrapping_shr(i), i < 8);

    running >>= 1;
}

pub fn shr_exact(self, rhs: u32) -> Option<u8>

🔬This is a nightly-only experimental API. (exact_bitshifts)

Exact shift right. Computes self >> rhs as long as it can be reversed losslessly.

Returns None if any non-zero bits would be shifted out or if rhs >= u8::BITS. Otherwise, returns Some(self >> rhs).

Examples

#![feature(exact_bitshifts)]

assert_eq!(0x10u8.shr_exact(4), Some(0x1));
assert_eq!(0x10u8.shr_exact(5), None);

pub unsafe fn unchecked_shr_exact(self, rhs: u32) -> u8

🔬This is a nightly-only experimental API. (exact_bitshifts)

Unchecked exact shift right. Computes self >> rhs, assuming the operation can be losslessly reversed and rhs cannot be larger than u8::BITS.

Safety

This results in undefined behavior when rhs > self.trailing_zeros() || rhs >= u8::BITS i.e. when u8::shr_exact would return None.

pub fn checked_pow(self, exp: u32) -> Option<u8>

Checked exponentiation. Computes self.pow(exp), returning None if overflow occurred.

Examples

assert_eq!(2u8.checked_pow(5), Some(32));
assert_eq!(0_u8.checked_pow(0), Some(1));
assert_eq!(u8::MAX.checked_pow(2), None);

pub fn strict_pow(self, exp: u32) -> u8

Strict exponentiation. Computes self.pow(exp), panicking if overflow occurred.

Panics

Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

Examples

assert_eq!(2u8.strict_pow(5), 32);
assert_eq!(0_u8.strict_pow(0), 1);

The following panics because of overflow:

let _ = u8::MAX.strict_pow(2);

pub fn saturating_add(self, rhs: u8) -> u8

Saturating integer addition. Computes self + rhs, saturating at the numeric bounds instead of overflowing.

Examples

assert_eq!(100u8.saturating_add(1), 101);
assert_eq!(u8::MAX.saturating_add(127), u8::MAX);

pub fn saturating_add_signed(self, rhs: i8) -> u8

Saturating addition with a signed integer. Computes self + rhs, saturating at the numeric bounds instead of overflowing.

Examples

assert_eq!(1u8.saturating_add_signed(2), 3);
assert_eq!(1u8.saturating_add_signed(-2), 0);
assert_eq!((u8::MAX - 2).saturating_add_signed(4), u8::MAX);

pub fn saturating_sub(self, rhs: u8) -> u8

Saturating integer subtraction. Computes self - rhs, saturating at the numeric bounds instead of overflowing.

Examples

assert_eq!(100u8.saturating_sub(27), 73);
assert_eq!(13u8.saturating_sub(127), 0);

pub fn saturating_sub_signed(self, rhs: i8) -> u8

Saturating integer subtraction. Computes self - rhs, saturating at the numeric bounds instead of overflowing.

Examples

assert_eq!(1u8.saturating_sub_signed(2), 0);
assert_eq!(1u8.saturating_sub_signed(-2), 3);
assert_eq!((u8::MAX - 2).saturating_sub_signed(-4), u8::MAX);

pub fn saturating_mul(self, rhs: u8) -> u8

Saturating integer multiplication. Computes self * rhs, saturating at the numeric bounds instead of overflowing.

Examples

assert_eq!(2u8.saturating_mul(10), 20);
assert_eq!((u8::MAX).saturating_mul(10), u8::MAX);

pub fn saturating_div(self, rhs: u8) -> u8

Saturating integer division. Computes self / rhs, saturating at the numeric bounds instead of overflowing.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(5u8.saturating_div(2), 2);

pub fn saturating_pow(self, exp: u32) -> u8

Saturating integer exponentiation. Computes self.pow(exp), saturating at the numeric bounds instead of overflowing.

Examples

assert_eq!(4u8.saturating_pow(3), 64);
assert_eq!(0_u8.saturating_pow(0), 1);
assert_eq!(u8::MAX.saturating_pow(2), u8::MAX);

pub fn wrapping_add(self, rhs: u8) -> u8

Wrapping (modular) addition. Computes self + rhs, wrapping around at the boundary of the type.

Examples

assert_eq!(200u8.wrapping_add(55), 255);
assert_eq!(200u8.wrapping_add(u8::MAX), 199);

pub fn wrapping_add_signed(self, rhs: i8) -> u8

Wrapping (modular) addition with a signed integer. Computes self + rhs, wrapping around at the boundary of the type.

Examples

assert_eq!(1u8.wrapping_add_signed(2), 3);
assert_eq!(1u8.wrapping_add_signed(-2), u8::MAX);
assert_eq!((u8::MAX - 2).wrapping_add_signed(4), 1);

pub fn wrapping_sub(self, rhs: u8) -> u8

Wrapping (modular) subtraction. Computes self - rhs, wrapping around at the boundary of the type.

Examples

assert_eq!(100u8.wrapping_sub(100), 0);
assert_eq!(100u8.wrapping_sub(u8::MAX), 101);

pub fn wrapping_sub_signed(self, rhs: i8) -> u8

Wrapping (modular) subtraction with a signed integer. Computes self - rhs, wrapping around at the boundary of the type.

Examples

assert_eq!(1u8.wrapping_sub_signed(2), u8::MAX);
assert_eq!(1u8.wrapping_sub_signed(-2), 3);
assert_eq!((u8::MAX - 2).wrapping_sub_signed(-4), 1);

pub fn wrapping_mul(self, rhs: u8) -> u8

Wrapping (modular) multiplication. Computes self * rhs, wrapping around at the boundary of the type.

Examples

Please note that this example is shared among integer types, which is why u8 is used.

assert_eq!(10u8.wrapping_mul(12), 120);
assert_eq!(25u8.wrapping_mul(12), 44);

pub fn wrapping_div(self, rhs: u8) -> u8

Wrapping (modular) division. Computes self / rhs.

Wrapped division on unsigned types is just normal division. There’s no way wrapping could ever happen. This function exists so that all operations are accounted for in the wrapping operations.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.wrapping_div(10), 10);

pub fn wrapping_div_euclid(self, rhs: u8) -> u8

Wrapping Euclidean division. Computes self.div_euclid(rhs).

Wrapped division on unsigned types is just normal division. There’s no way wrapping could ever happen. This function exists so that all operations are accounted for in the wrapping operations. Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self.wrapping_div(rhs).

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.wrapping_div_euclid(10), 10);

pub fn wrapping_rem(self, rhs: u8) -> u8

Wrapping (modular) remainder. Computes self % rhs.

Wrapped remainder calculation on unsigned types is just the regular remainder calculation. There’s no way wrapping could ever happen. This function exists so that all operations are accounted for in the wrapping operations.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.wrapping_rem(10), 0);

pub fn wrapping_rem_euclid(self, rhs: u8) -> u8

Wrapping Euclidean modulo. Computes self.rem_euclid(rhs).

Wrapped modulo calculation on unsigned types is just the regular remainder calculation. There’s no way wrapping could ever happen. This function exists so that all operations are accounted for in the wrapping operations. Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self.wrapping_rem(rhs).

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(100u8.wrapping_rem_euclid(10), 0);

pub fn wrapping_neg(self) -> u8

Wrapping (modular) negation. Computes -self, wrapping around at the boundary of the type.

Since unsigned types do not have negative equivalents all applications of this function will wrap (except for -0). For values smaller than the corresponding signed type’s maximum the result is the same as casting the corresponding signed value. Any larger values are equivalent to MAX + 1 - (val - MAX - 1) where MAX is the corresponding signed type’s maximum.

Examples

assert_eq!(0_u8.wrapping_neg(), 0);
assert_eq!(u8::MAX.wrapping_neg(), 1);
assert_eq!(13_u8.wrapping_neg(), (!13) + 1);
assert_eq!(42_u8.wrapping_neg(), !(42 - 1));

pub fn wrapping_shl(self, rhs: u32) -> u8

Panic-free bitwise shift-left; yields self << mask(rhs), where mask removes any high-order bits of rhs that would cause the shift to exceed the bitwidth of the type.

Beware that, unlike most other wrapping_* methods on integers, this does not give the same result as doing the shift in infinite precision then truncating as needed. Instead, the behaviour of this method matches what shift instructions do on many processors, and is what the << operator does when overflow checks are disabled, but numerically it’s weird. Consider, instead, using Self::unbounded_shl which has nicer behaviour.

Note that this is not the same as a rotate-left; the RHS of a wrapping shift-left is restricted to the range of the type, rather than the bits shifted out of the LHS being returned to the other end. The primitive integer types all implement a rotate_left function, which may be what you want instead.

Examples

assert_eq!(1_u8.wrapping_shl(7), 128);
assert_eq!(0b101_u8.wrapping_shl(0), 0b101);
assert_eq!(0b101_u8.wrapping_shl(1), 0b1010);
assert_eq!(0b101_u8.wrapping_shl(2), 0b10100);
assert_eq!(u8::MAX.wrapping_shl(2), u8::MAX - 3);
assert_eq!(42_u8.wrapping_shl(8), 42);
assert_eq!(42_u8.wrapping_shl(1).wrapping_shl(7), 0);
assert_eq!(1_u8.wrapping_shl(128), 1);
assert_eq!(5_u8.wrapping_shl(1025), 10);

pub fn wrapping_shr(self, rhs: u32) -> u8

Panic-free bitwise shift-right; yields self >> mask(rhs), where mask removes any high-order bits of rhs that would cause the shift to exceed the bitwidth of the type.

Beware that, unlike most other wrapping_* methods on integers, this does not give the same result as doing the shift in infinite precision then truncating as needed. Instead, the behaviour of this method matches what shift instructions do on many processors, and is what the >> operator does when overflow checks are disabled, but numerically it’s weird. Consider, instead, using Self::unbounded_shr which has nicer behaviour.

Note that this is not the same as a rotate-right; the RHS of a wrapping shift-right is restricted to the range of the type, rather than the bits shifted out of the LHS being returned to the other end. The primitive integer types all implement a rotate_right function, which may be what you want instead.

Examples

assert_eq!(128_u8.wrapping_shr(7), 1);
assert_eq!(0b1010_u8.wrapping_shr(0), 0b1010);
assert_eq!(0b1010_u8.wrapping_shr(1), 0b101);
assert_eq!(0b1010_u8.wrapping_shr(2), 0b10);
assert_eq!(u8::MAX.wrapping_shr(1), i8::MAX.cast_unsigned());
assert_eq!(42_u8.wrapping_shr(8), 42);
assert_eq!(42_u8.wrapping_shr(1).wrapping_shr(7), 0);
assert_eq!(128_u8.wrapping_shr(128), 128);
assert_eq!(10_u8.wrapping_shr(1025), 5);

pub fn wrapping_pow(self, exp: u32) -> u8

Wrapping (modular) exponentiation. Computes self.pow(exp), wrapping around at the boundary of the type.

Examples

assert_eq!(3u8.wrapping_pow(5), 243);
assert_eq!(3u8.wrapping_pow(6), 217);
assert_eq!(0_u8.wrapping_pow(0), 1);

pub fn overflowing_add(self, rhs: u8) -> (u8, bool)

Calculates self + rhs.

Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

assert_eq!(5u8.overflowing_add(2), (7, false));
assert_eq!(u8::MAX.overflowing_add(1), (0, true));

pub fn carrying_add(self, rhs: u8, carry: bool) -> (u8, bool)

Calculates self + rhs + carry and returns a tuple containing the sum and the output carry (in that order).

Performs “ternary addition” of two integer operands and a carry-in bit, and returns an output integer and a carry-out bit. This allows chaining together multiple additions to create a wider addition, and can be useful for bignum addition.

This can be thought of as a 8-bit “full adder”, in the electronics sense.

If the input carry is false, this method is equivalent to overflowing_add, and the output carry is equal to the overflow flag. Note that although carry and overflow flags are similar for unsigned integers, they are different for signed integers.

Examples

//    3  MAX    (a = 3 × 2^8 + 2^8 - 1)
// +  5    7    (b = 5 × 2^8 + 7)
// ---------
//    9    6    (sum = 9 × 2^8 + 6)

let (a1, a0): (u8, u8) = (3, u8::MAX);
let (b1, b0): (u8, u8) = (5, 7);
let carry0 = false;

let (sum0, carry1) = a0.carrying_add(b0, carry0);
assert_eq!(carry1, true);
let (sum1, carry2) = a1.carrying_add(b1, carry1);
assert_eq!(carry2, false);

assert_eq!((sum1, sum0), (9, 6));

pub fn overflowing_add_signed(self, rhs: i8) -> (u8, bool)

Calculates self + rhs with a signed rhs.

Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

assert_eq!(1u8.overflowing_add_signed(2), (3, false));
assert_eq!(1u8.overflowing_add_signed(-2), (u8::MAX, true));
assert_eq!((u8::MAX - 2).overflowing_add_signed(4), (1, true));

pub fn overflowing_sub(self, rhs: u8) -> (u8, bool)

Calculates self - rhs.

Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

assert_eq!(5u8.overflowing_sub(2), (3, false));
assert_eq!(0u8.overflowing_sub(1), (u8::MAX, true));

pub fn borrowing_sub(self, rhs: u8, borrow: bool) -> (u8, bool)

Calculates self − rhs − borrow and returns a tuple containing the difference and the output borrow.

Performs “ternary subtraction” by subtracting both an integer operand and a borrow-in bit from self, and returns an output integer and a borrow-out bit. This allows chaining together multiple subtractions to create a wider subtraction, and can be useful for bignum subtraction.

Examples

//    9    6    (a = 9 × 2^8 + 6)
// -  5    7    (b = 5 × 2^8 + 7)
// ---------
//    3  MAX    (diff = 3 × 2^8 + 2^8 - 1)

let (a1, a0): (u8, u8) = (9, 6);
let (b1, b0): (u8, u8) = (5, 7);
let borrow0 = false;

let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
assert_eq!(borrow1, true);
let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
assert_eq!(borrow2, false);

assert_eq!((diff1, diff0), (3, u8::MAX));

pub fn overflowing_sub_signed(self, rhs: i8) -> (u8, bool)

Calculates self - rhs with a signed rhs

Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

Examples

assert_eq!(1u8.overflowing_sub_signed(2), (u8::MAX, true));
assert_eq!(1u8.overflowing_sub_signed(-2), (3, false));
assert_eq!((u8::MAX - 2).overflowing_sub_signed(-4), (1, true));

pub fn abs_diff(self, other: u8) -> u8

Computes the absolute difference between self and other.

Examples

assert_eq!(100u8.abs_diff(80), 20u8);
assert_eq!(100u8.abs_diff(110), 10u8);

pub fn overflowing_mul(self, rhs: u8) -> (u8, bool)

Calculates the multiplication of self and rhs.

Returns a tuple of the multiplication along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

If you want the value of the overflow, rather than just whether an overflow occurred, see Self::carrying_mul.

Examples

Please note that this example is shared among integer types, which is why u32 is used.

assert_eq!(5u32.overflowing_mul(2), (10, false));
assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));

pub fn carrying_mul(self, rhs: u8, carry: u8) -> (u8, u8)

Calculates the “full multiplication” self * rhs + carry without the possibility to overflow.

This returns the low-order (wrapping) bits and the high-order (overflow) bits of the result as two separate values, in that order.

Performs “long multiplication” which takes in an extra amount to add, and may return an additional amount of overflow. This allows for chaining together multiple multiplications to create “big integers” which represent larger values.

If you also need to add a value, then use Self::carrying_mul_add.

Examples

Please note that this example is shared among integer types, which is why u32 is used.

assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
assert_eq!(u8::MAX.carrying_mul(u8::MAX, u8::MAX), (0, u8::MAX));

This is the core operation needed for scalar multiplication when implementing it for wider-than-native types.

fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
    let mut carry = 0;
    for d in little_endian_digits.iter_mut() {
        (*d, carry) = d.carrying_mul(multiplicand, carry);
    }
    if carry != 0 {
        little_endian_digits.push(carry);
    }
}

let mut v = vec![10, 20];
scalar_mul_eq(&mut v, 3);
assert_eq!(v, [30, 60]);

assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
let mut v = vec![0x4321, 0x8765];
scalar_mul_eq(&mut v, 0xFEED);
assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);

If carry is zero, this is similar to overflowing_mul, except that it gives the value of the overflow instead of just whether one happened:

#![feature(const_unsigned_bigint_helpers)]
let r = u8::carrying_mul(7, 13, 0);
assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
let r = u8::carrying_mul(13, 42, 0);
assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));

The value of the first field in the returned tuple matches what you’d get by combining the wrapping_mul and wrapping_add methods:

#![feature(const_unsigned_bigint_helpers)]
assert_eq!(
    789_u16.carrying_mul(456, 123).0,
    789_u16.wrapping_mul(456).wrapping_add(123),
);

pub fn carrying_mul_add(self, rhs: u8, carry: u8, add: u8) -> (u8, u8)

Calculates the “full multiplication” self * rhs + carry + add.

This returns the low-order (wrapping) bits and the high-order (overflow) bits of the result as two separate values, in that order.

This cannot overflow, as the double-width result has exactly enough space for the largest possible result. This is equivalent to how, in decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.

Performs “long multiplication” which takes in an extra amount to add, and may return an additional amount of overflow. This allows for chaining together multiple multiplications to create “big integers” which represent larger values.

If you don’t need the add part, then you can use Self::carrying_mul instead.

Examples

Please note that this example is shared between integer types, which explains why u32 is used here.

assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
assert_eq!(u8::MAX.carrying_mul_add(u8::MAX, u8::MAX, u8::MAX), (u8::MAX, u8::MAX));

This is the core per-digit operation for “grade school” O(n²) multiplication.

Please note that this example is shared between integer types, using u8 for simplicity of the demonstration.

fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
    let mut out = [0; N];
    for j in 0..N {
        let mut carry = 0;
        for i in 0..(N - j) {
            (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
        }
    }
    out
}

// -1 * -1 == 1
assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);

assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
assert_eq!(
    quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
    u32::to_le_bytes(0xcffc982d)
);

pub fn overflowing_div(self, rhs: u8) -> (u8, bool)

Calculates the divisor when self is divided by rhs.

Returns a tuple of the divisor along with a boolean indicating whether an arithmetic overflow would occur. Note that for unsigned integers overflow never occurs, so the second value is always false.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(5u8.overflowing_div(2), (2, false));

pub fn overflowing_div_euclid(self, rhs: u8) -> (u8, bool)

Calculates the quotient of Euclidean division self.div_euclid(rhs).

Returns a tuple of the divisor along with a boolean indicating whether an arithmetic overflow would occur. Note that for unsigned integers overflow never occurs, so the second value is always false. Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self.overflowing_div(rhs).

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(5u8.overflowing_div_euclid(2), (2, false));

pub fn overflowing_rem(self, rhs: u8) -> (u8, bool)

Calculates the remainder when self is divided by rhs.

Returns a tuple of the remainder after dividing along with a boolean indicating whether an arithmetic overflow would occur. Note that for unsigned integers overflow never occurs, so the second value is always false.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(5u8.overflowing_rem(2), (1, false));

pub fn overflowing_rem_euclid(self, rhs: u8) -> (u8, bool)

Calculates the remainder self.rem_euclid(rhs) as if by Euclidean division.

Returns a tuple of the modulo after dividing along with a boolean indicating whether an arithmetic overflow would occur. Note that for unsigned integers overflow never occurs, so the second value is always false. Since, for the positive integers, all common definitions of division are equal, this operation is exactly equal to self.overflowing_rem(rhs).

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(5u8.overflowing_rem_euclid(2), (1, false));

pub fn overflowing_neg(self) -> (u8, bool)

Negates self in an overflowing fashion.

Returns !self + 1 using wrapping operations to return the value that represents the negation of this unsigned value. Note that for positive unsigned values overflow always occurs, but negating 0 does not overflow.

Examples

assert_eq!(0u8.overflowing_neg(), (0, false));
assert_eq!(2u8.overflowing_neg(), (-2i32 as u8, true));

pub fn overflowing_shl(self, rhs: u32) -> (u8, bool)

Shifts self left by rhs bits.

Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.

Examples

assert_eq!(0x1u8.overflowing_shl(4), (0x10, false));
assert_eq!(0x1u8.overflowing_shl(132), (0x10, true));
assert_eq!(0x10u8.overflowing_shl(7), (0, false));

pub fn overflowing_shr(self, rhs: u32) -> (u8, bool)

Shifts self right by rhs bits.

Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.

Examples

assert_eq!(0x10u8.overflowing_shr(4), (0x1, false));
assert_eq!(0x10u8.overflowing_shr(132), (0x1, true));

pub fn overflowing_pow(self, exp: u32) -> (u8, bool)

Raises self to the power of exp, using exponentiation by squaring.

Returns a tuple of the exponentiation along with a bool indicating whether an overflow happened.

Examples

assert_eq!(3u8.overflowing_pow(5), (243, false));
assert_eq!(0_u8.overflowing_pow(0), (1, false));
assert_eq!(3u8.overflowing_pow(6), (217, true));

pub fn pow(self, exp: u32) -> u8

Raises self to the power of exp, using exponentiation by squaring.

Examples

assert_eq!(2u8.pow(5), 32);
assert_eq!(0_u8.pow(0), 1);

pub fn isqrt(self) -> u8

Returns the square root of the number, rounded down.

Examples

assert_eq!(10u8.isqrt(), 3);

pub fn div_euclid(self, rhs: u8) -> u8

Performs Euclidean division.

Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self / rhs.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(7u8.div_euclid(4), 1); // or any other integer type

pub fn rem_euclid(self, rhs: u8) -> u8

Calculates the least remainder of self when divided by rhs.

Since, for the positive integers, all common definitions of division are equal, this is exactly equal to self % rhs.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(7u8.rem_euclid(4), 3); // or any other integer type

pub fn div_floor(self, rhs: u8) -> u8

🔬This is a nightly-only experimental API. (int_roundings)

Calculates the quotient of self and rhs, rounding the result towards negative infinity.

This is the same as performing self / rhs for all unsigned integers.

Panics

This function will panic if rhs is zero.

Examples

#![feature(int_roundings)]
assert_eq!(7_u8.div_floor(4), 1);

pub fn div_ceil(self, rhs: u8) -> u8

Calculates the quotient of self and rhs, rounding the result towards positive infinity.

Panics

This function will panic if rhs is zero.

Examples

assert_eq!(7_u8.div_ceil(4), 2);

pub fn next_multiple_of(self, rhs: u8) -> u8

Calculates the smallest value greater than or equal to self that is a multiple of rhs.

Panics

This function will panic if rhs is zero.

Overflow behavior

On overflow, this function will panic if overflow checks are enabled (default in debug mode) and wrap if overflow checks are disabled (default in release mode).

Examples

assert_eq!(16_u8.next_multiple_of(8), 16);
assert_eq!(23_u8.next_multiple_of(8), 24);

pub fn checked_next_multiple_of(self, rhs: u8) -> Option<u8>

Calculates the smallest value greater than or equal to self that is a multiple of rhs. Returns None if rhs is zero or the operation would result in overflow.

Examples

assert_eq!(16_u8.checked_next_multiple_of(8), Some(16));
assert_eq!(23_u8.checked_next_multiple_of(8), Some(24));
assert_eq!(1_u8.checked_next_multiple_of(0), None);
assert_eq!(u8::MAX.checked_next_multiple_of(2), None);

pub fn is_multiple_of(self, rhs: u8) -> bool

Returns true if self is an integer multiple of rhs, and false otherwise.

This function is equivalent to self % rhs == 0, except that it will not panic for rhs == 0. Instead, 0.is_multiple_of(0) == true, and for any non-zero n, n.is_multiple_of(0) == false.

Examples

assert!(6_u8.is_multiple_of(2));
assert!(!5_u8.is_multiple_of(2));

assert!(0_u8.is_multiple_of(0));
assert!(!6_u8.is_multiple_of(0));

pub fn is_power_of_two(self) -> bool

Returns true if and only if self == 2^k for some unsigned integer k.

Examples

assert!(16u8.is_power_of_two());
assert!(!10u8.is_power_of_two());

pub fn next_power_of_two(self) -> u8

Returns the smallest power of two greater than or equal to self.

When return value overflows (i.e., self > (1 << (N-1)) for type uN), it panics in debug mode and the return value is wrapped to 0 in release mode (the only situation in which this method can return 0).

Examples

assert_eq!(2u8.next_power_of_two(), 2);
assert_eq!(3u8.next_power_of_two(), 4);
assert_eq!(0u8.next_power_of_two(), 1);

pub fn checked_next_power_of_two(self) -> Option<u8>

Returns the smallest power of two greater than or equal to self. If the next power of two is greater than the type’s maximum value, None is returned, otherwise the power of two is wrapped in Some.

Examples

assert_eq!(2u8.checked_next_power_of_two(), Some(2));
assert_eq!(3u8.checked_next_power_of_two(), Some(4));
assert_eq!(u8::MAX.checked_next_power_of_two(), None);

pub fn wrapping_next_power_of_two(self) -> u8

🔬This is a nightly-only experimental API. (wrapping_next_power_of_two)

Returns the smallest power of two greater than or equal to n. If the next power of two is greater than the type’s maximum value, the return value is wrapped to 0.

Examples

#![feature(wrapping_next_power_of_two)]

assert_eq!(2u8.wrapping_next_power_of_two(), 2);
assert_eq!(3u8.wrapping_next_power_of_two(), 4);
assert_eq!(u8::MAX.wrapping_next_power_of_two(), 0);

pub fn to_be_bytes(self) -> [u8; 1]

Returns the memory representation of this integer as a byte array in big-endian (network) byte order.

Note: This function is meaningless on u8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types.

Examples

let bytes = 0x12u8.to_be_bytes();
assert_eq!(bytes, [0x12]);

pub fn to_le_bytes(self) -> [u8; 1]

Returns the memory representation of this integer as a byte array in little-endian byte order.

Note: This function is meaningless on u8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types.

Examples

let bytes = 0x12u8.to_le_bytes();
assert_eq!(bytes, [0x12]);

pub fn to_ne_bytes(self) -> [u8; 1]

Returns the memory representation of this integer as a byte array in native byte order.

As the target platform’s native endianness is used, portable code should use to_be_bytes or to_le_bytes, as appropriate, instead.

Note: This function is meaningless on u8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types.

Examples

let bytes = 0x12u8.to_ne_bytes();
assert_eq!(
    bytes,
    if cfg!(target_endian = "big") {
        [0x12]
    } else {
        [0x12]
    }
);

pub fn truncate<Target>(self) -> Target

where u8: TruncateTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate)

Truncate an integer to an integer of the same size or smaller, preserving the least significant bits.

Examples

#![feature(integer_widen_truncate)]
assert_eq!(120u8, 120u8.truncate());
assert_eq!(120u8, 376u32.truncate());

pub fn saturating_truncate<Target>(self) -> Target

where u8: TruncateTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate)

Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds instead of truncating.

Examples

#![feature(integer_widen_truncate)]
assert_eq!(120u8, 120u8.saturating_truncate());
assert_eq!(255u8, 376u32.saturating_truncate());

pub fn checked_truncate<Target>(self) -> Option<Target>

where u8: TruncateTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate)

Truncate an integer to an integer of the same size or smaller, returning None if the value is outside the bounds of the smaller type.

Examples

#![feature(integer_widen_truncate)]
assert_eq!(Some(120u8), 120u8.checked_truncate());
assert_eq!(None, 376u32.checked_truncate::<u8>());

pub fn widen<Target>(self) -> Target

where u8: WidenTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate)

Widen to an integer of the same size or larger, preserving its value.

Examples

#![feature(integer_widen_truncate)]
assert_eq!(120u128, 120u8.widen());

pub fn saturating_cast<T>(self) -> T

where T: BoundedCastFromInt<u8>,

🔬This is a nightly-only experimental API. (integer_casts)

Converts self to the target integer type, saturating at the numeric bounds instead of overflowing.

Examples

#![feature(integer_casts)]
assert_eq!(255u8, u8::MAX.saturating_cast());
assert_eq!(127i8, u8::MAX.saturating_cast());
assert_eq!(42i8, 42u8.saturating_cast());

pub fn wrapping_cast<T>(self) -> T

where T: BoundedCastFromInt<u8>,

🔬This is a nightly-only experimental API. (integer_casts)

Converts self to the target integer type, wrapping around at the boundary of the target type.

Examples

#![feature(integer_casts)]
assert_eq!(255u8, u8::MAX.wrapping_cast());
assert_eq!(42i8, 42u8.wrapping_cast());
assert_eq!(u8::MAX as i8, u8::MAX.wrapping_cast());

pub fn checked_cast<T>(self) -> Option<T>

where T: CheckedCastFromInt<u8>,

🔬This is a nightly-only experimental API. (integer_casts)

Converts self to the target integer type, returning None if the value is not representable by the target type.

Examples

#![feature(integer_casts)]
assert_eq!(Some(42u8), 42u8.checked_cast());
assert_eq!(128u8.checked_cast::<i8>(), None);

pub fn strict_cast<T>(self) -> T

where T: CheckedCastFromInt<u8>,

🔬This is a nightly-only experimental API. (integer_casts)

Converts self to the target integer type, panicking if the value is not representable by the target type.

Panics

This function will panic if the value is not representable by the target type.

Examples

#![feature(integer_casts)]
assert_eq!(42u8, 42u8.strict_cast());

The following will panic:

#![feature(integer_casts)]
let _ = 128u8.strict_cast::<i8>();

pub unsafe fn unchecked_cast<T>(self) -> T

where T: CheckedCastFromInt<u8>,

🔬This is a nightly-only experimental API. (integer_casts)

Converts self to the target integer type, assuming the value is representable by the target type.

Safety

This results in undefined behavior if the integer value of self is bigger than T::MAX, or smaller than T::MIN, where T is the target type.

pub fn midpoint(self, rhs: u8) -> u8

Calculates the midpoint (average) between self and rhs.

midpoint(a, b) is (a + b) / 2 as if it were performed in a sufficiently-large unsigned integral type. This implies that the result is always rounded towards zero and that no overflow will ever occur.

Examples

assert_eq!(0u8.midpoint(4), 2);
assert_eq!(1u8.midpoint(4), 2);

pub fn widening_mul(self, rhs: u8) -> u16

🔬This is a nightly-only experimental API. (widening_mul)

Widening multiplication. Computes self * rhs, widening to a larger integer.

The returned value is always exact and can never overflow.

Note that this method is semantically equivalent to carrying_mul with a carry of zero, with the latter instead returning a tuple denoting the low and high parts of the result. Consider using it instead if you need interoperability with other big int helper functions, or if this method isn’t available for a given type.

Examples

#![feature(widening_mul)]

assert_eq!(u8::MAX.widening_mul(0_u8), 0);
assert_eq!(u8::MAX.widening_mul(u8::MAX), u8::MAX as u16 * u8::MAX as u16);

pub fn widening_carryless_mul(self, rhs: u8) -> u16

🔬This is a nightly-only experimental API. (uint_carryless_mul)

Performs a widening carry-less multiplication.

Examples

#![feature(uint_carryless_mul)]

assert_eq!(u8::MAX.widening_carryless_mul(u8::MAX), u16::MAX / 3);

pub fn carrying_carryless_mul(self, rhs: u8, carry: u8) -> (u8, u8)

🔬This is a nightly-only experimental API. (uint_carryless_mul)

Calculates the “full carryless multiplication” without the possibility to overflow.

This returns the low-order (wrapping) bits and the high-order (overflow) bits of the result as two separate values, in that order.

Examples

Please note that this example is shared among integer types, which is why u8 is used.

#![feature(uint_carryless_mul)]

assert_eq!(0b1000_0000u8.carrying_carryless_mul(0b1000_0000, 0b0000), (0, 0b0100_0000));
assert_eq!(0b1000_0000u8.carrying_carryless_mul(0b1000_0000, 0b1111), (0b1111, 0b0100_0000));
assert_eq!(u8::MAX.carrying_carryless_mul(u8::MAX, u8::MAX), (!(u8::MAX / 3), u8::MAX / 3));

pub fn is_ascii(&self) -> bool

Checks if the value is within the ASCII range.

Examples

let ascii = 97u8;
let non_ascii = 150u8;

assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());

pub fn as_ascii(&self) -> Option<AsciiChar>

🔬This is a nightly-only experimental API. (ascii_char)

If the value of this byte is within the ASCII range, returns it as an ASCII character. Otherwise, returns None.

pub unsafe fn as_ascii_unchecked(&self) -> AsciiChar

🔬This is a nightly-only experimental API. (ascii_char)

Converts this byte to an ASCII character, without checking whether or not it’s valid.

Safety

This byte must be valid ASCII, or else this is UB.

pub fn to_ascii_uppercase(&self) -> u8

Makes a copy of the value in its ASCII upper case equivalent.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To uppercase the value in-place, use make_ascii_uppercase.

Examples

let lowercase_a = 97u8;

assert_eq!(65, lowercase_a.to_ascii_uppercase());

pub fn to_ascii_lowercase(&self) -> u8

Makes a copy of the value in its ASCII lower case equivalent.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To lowercase the value in-place, use make_ascii_lowercase.

Examples

let uppercase_a = 65u8;

assert_eq!(97, uppercase_a.to_ascii_lowercase());

pub fn eq_ignore_ascii_case(&self, other: &u8) -> bool

Checks that two values are an ASCII case-insensitive match.

This is equivalent to to_ascii_lowercase(a) == to_ascii_lowercase(b).

Examples

let lowercase_a = 97u8;
let uppercase_a = 65u8;

assert!(lowercase_a.eq_ignore_ascii_case(&uppercase_a));

pub fn make_ascii_uppercase(&mut self)

Converts this value to its ASCII upper case equivalent in-place.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use to_ascii_uppercase.

Examples

let mut byte = b'a';

byte.make_ascii_uppercase();

assert_eq!(b'A', byte);

pub fn make_ascii_lowercase(&mut self)

Converts this value to its ASCII lower case equivalent in-place.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use to_ascii_lowercase.

Examples

let mut byte = b'A';

byte.make_ascii_lowercase();

assert_eq!(b'a', byte);

pub fn is_ascii_alphabetic(&self) -> bool

Checks if the value is an ASCII alphabetic character:

• U+0041 ‘A’ ..= U+005A ‘Z’, or
• U+0061 ‘a’ ..= U+007A ‘z’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(uppercase_a.is_ascii_alphabetic());
assert!(uppercase_g.is_ascii_alphabetic());
assert!(a.is_ascii_alphabetic());
assert!(g.is_ascii_alphabetic());
assert!(!zero.is_ascii_alphabetic());
assert!(!percent.is_ascii_alphabetic());
assert!(!space.is_ascii_alphabetic());
assert!(!lf.is_ascii_alphabetic());
assert!(!esc.is_ascii_alphabetic());

pub fn is_ascii_uppercase(&self) -> bool

Checks if the value is an ASCII uppercase character: U+0041 ‘A’ ..= U+005A ‘Z’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(uppercase_a.is_ascii_uppercase());
assert!(uppercase_g.is_ascii_uppercase());
assert!(!a.is_ascii_uppercase());
assert!(!g.is_ascii_uppercase());
assert!(!zero.is_ascii_uppercase());
assert!(!percent.is_ascii_uppercase());
assert!(!space.is_ascii_uppercase());
assert!(!lf.is_ascii_uppercase());
assert!(!esc.is_ascii_uppercase());

pub fn is_ascii_lowercase(&self) -> bool

Checks if the value is an ASCII lowercase character: U+0061 ‘a’ ..= U+007A ‘z’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(!uppercase_a.is_ascii_lowercase());
assert!(!uppercase_g.is_ascii_lowercase());
assert!(a.is_ascii_lowercase());
assert!(g.is_ascii_lowercase());
assert!(!zero.is_ascii_lowercase());
assert!(!percent.is_ascii_lowercase());
assert!(!space.is_ascii_lowercase());
assert!(!lf.is_ascii_lowercase());
assert!(!esc.is_ascii_lowercase());

pub fn is_ascii_alphanumeric(&self) -> bool

Checks if the value is an ASCII alphanumeric character:

• U+0041 ‘A’ ..= U+005A ‘Z’, or
• U+0061 ‘a’ ..= U+007A ‘z’, or
• U+0030 ‘0’ ..= U+0039 ‘9’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(uppercase_a.is_ascii_alphanumeric());
assert!(uppercase_g.is_ascii_alphanumeric());
assert!(a.is_ascii_alphanumeric());
assert!(g.is_ascii_alphanumeric());
assert!(zero.is_ascii_alphanumeric());
assert!(!percent.is_ascii_alphanumeric());
assert!(!space.is_ascii_alphanumeric());
assert!(!lf.is_ascii_alphanumeric());
assert!(!esc.is_ascii_alphanumeric());

pub fn is_ascii_digit(&self) -> bool

Checks if the value is an ASCII decimal digit: U+0030 ‘0’ ..= U+0039 ‘9’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(!uppercase_a.is_ascii_digit());
assert!(!uppercase_g.is_ascii_digit());
assert!(!a.is_ascii_digit());
assert!(!g.is_ascii_digit());
assert!(zero.is_ascii_digit());
assert!(!percent.is_ascii_digit());
assert!(!space.is_ascii_digit());
assert!(!lf.is_ascii_digit());
assert!(!esc.is_ascii_digit());

pub fn is_ascii_octdigit(&self) -> bool

🔬This is a nightly-only experimental API. (is_ascii_octdigit)

Checks if the value is an ASCII octal digit: U+0030 ‘0’ ..= U+0037 ‘7’.

Examples

#![feature(is_ascii_octdigit)]

let uppercase_a = b'A';
let a = b'a';
let zero = b'0';
let seven = b'7';
let nine = b'9';
let percent = b'%';
let lf = b'\n';

assert!(!uppercase_a.is_ascii_octdigit());
assert!(!a.is_ascii_octdigit());
assert!(zero.is_ascii_octdigit());
assert!(seven.is_ascii_octdigit());
assert!(!nine.is_ascii_octdigit());
assert!(!percent.is_ascii_octdigit());
assert!(!lf.is_ascii_octdigit());

pub fn is_ascii_hexdigit(&self) -> bool

Checks if the value is an ASCII hexadecimal digit:

• U+0030 ‘0’ ..= U+0039 ‘9’, or
• U+0041 ‘A’ ..= U+0046 ‘F’, or
• U+0061 ‘a’ ..= U+0066 ‘f’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(uppercase_a.is_ascii_hexdigit());
assert!(!uppercase_g.is_ascii_hexdigit());
assert!(a.is_ascii_hexdigit());
assert!(!g.is_ascii_hexdigit());
assert!(zero.is_ascii_hexdigit());
assert!(!percent.is_ascii_hexdigit());
assert!(!space.is_ascii_hexdigit());
assert!(!lf.is_ascii_hexdigit());
assert!(!esc.is_ascii_hexdigit());

pub fn is_ascii_punctuation(&self) -> bool

Checks if the value is an ASCII punctuation or symbol character (i.e. not alphanumeric, whitespace, or control):

• U+0021 ..= U+002F ! " # $ % & ' ( ) * + , - . /, or
• U+003A ..= U+0040 : ; < = > ? @, or
• U+005B ..= U+0060 [ \ ] ^ _ `, or
• U+007B ..= U+007E { | } ~

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(!uppercase_a.is_ascii_punctuation());
assert!(!uppercase_g.is_ascii_punctuation());
assert!(!a.is_ascii_punctuation());
assert!(!g.is_ascii_punctuation());
assert!(!zero.is_ascii_punctuation());
assert!(percent.is_ascii_punctuation());
assert!(!space.is_ascii_punctuation());
assert!(!lf.is_ascii_punctuation());
assert!(!esc.is_ascii_punctuation());

pub fn is_ascii_graphic(&self) -> bool

Checks if the value is an ASCII graphic character (i.e. not whitespace or control): U+0021 ‘!’ ..= U+007E ‘~’.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(uppercase_a.is_ascii_graphic());
assert!(uppercase_g.is_ascii_graphic());
assert!(a.is_ascii_graphic());
assert!(g.is_ascii_graphic());
assert!(zero.is_ascii_graphic());
assert!(percent.is_ascii_graphic());
assert!(!space.is_ascii_graphic());
assert!(!lf.is_ascii_graphic());
assert!(!esc.is_ascii_graphic());

pub fn is_ascii_whitespace(&self) -> bool

Checks if the value is an ASCII whitespace character: U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED, U+000C FORM FEED, or U+000D CARRIAGE RETURN.

Warning: Because the list above excludes U+000B VERTICAL TAB, b.is_ascii_whitespace() is not equivalent to char::from(b).is_whitespace().

Rust uses the WhatWG Infra Standard’s definition of ASCII whitespace. There are several other definitions in wide use. For instance, the POSIX locale includes U+000B VERTICAL TAB as well as all the above characters, but—from the very same specification—the default rule for “field splitting” in the Bourne shell considers only SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.

If you are writing a program that will process an existing file format, check what that format’s definition of whitespace is before using this function.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(!uppercase_a.is_ascii_whitespace());
assert!(!uppercase_g.is_ascii_whitespace());
assert!(!a.is_ascii_whitespace());
assert!(!g.is_ascii_whitespace());
assert!(!zero.is_ascii_whitespace());
assert!(!percent.is_ascii_whitespace());
assert!(space.is_ascii_whitespace());
assert!(lf.is_ascii_whitespace());
assert!(!esc.is_ascii_whitespace());

pub fn is_ascii_control(&self) -> bool

Checks if the value is an ASCII control character: U+0000 NUL ..= U+001F UNIT SEPARATOR, or U+007F DELETE. Note that most ASCII whitespace characters are control characters, but SPACE is not.

Examples

let uppercase_a = b'A';
let uppercase_g = b'G';
let a = b'a';
let g = b'g';
let zero = b'0';
let percent = b'%';
let space = b' ';
let lf = b'\n';
let esc = b'\x1b';

assert!(!uppercase_a.is_ascii_control());
assert!(!uppercase_g.is_ascii_control());
assert!(!a.is_ascii_control());
assert!(!g.is_ascii_control());
assert!(!zero.is_ascii_control());
assert!(!percent.is_ascii_control());
assert!(!space.is_ascii_control());
assert!(lf.is_ascii_control());
assert!(esc.is_ascii_control());

pub fn escape_ascii(self) -> EscapeDefault

Returns an iterator that produces an escaped version of a u8, treating it as an ASCII character.

The behavior is identical to ascii::escape_default.

Examples

assert_eq!("0", b'0'.escape_ascii().to_string());
assert_eq!("\\t", b'\t'.escape_ascii().to_string());
assert_eq!("\\r", b'\r'.escape_ascii().to_string());
assert_eq!("\\n", b'\n'.escape_ascii().to_string());
assert_eq!("\\'", b'\''.escape_ascii().to_string());
assert_eq!("\\\"", b'"'.escape_ascii().to_string());
assert_eq!("\\\\", b'\\'.escape_ascii().to_string());
assert_eq!("\\x9d", b'\x9d'.escape_ascii().to_string());

pub fn format_into(self, buf: &mut NumBuffer<u8>) -> &str

Formats this integer as an unsigned decimal number, using the memory pointed to by buf as storage for the returned string slice.

This method can be used to convert integers to strings without involving the dynamic dispatch that using Display would. This may be more efficient in situations where fmt is not otherwise used.

Examples

use core::fmt::NumBuffer;

let n = 0u8;
let mut buf = NumBuffer::new();
assert_eq!(n.format_into(&mut buf), "0");

let n1 = 32u8;
assert_eq!(n1.format_into(&mut buf), "32");

let n2 = u8 :: MAX;
assert_eq!(n2.format_into(&mut buf), u8 :: MAX.to_string());

Trait Implementations

impl Clone for TextOpacity

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Component for TextOpacity

where Self: Send + Sync + 'static,

const STORAGE_TYPE: StorageType = bevy_ecs::component::StorageType::Table

A constant indicating the storage type used for this component.

type Mutability = Mutable

A marker type to assist Bevy with determining if this component is mutable, or immutable. Mutable components will have [Component<Mutability = Mutable>], while immutable components will instead have [Component<Mutability = Immutable>].

fn register_required_components( _requiree: ComponentId, required_components: &mut RequiredComponentsRegistrator<'_, '_>, )

Registers required components.

fn clone_behavior() -> ComponentCloneBehavior

Called when registering this component, allowing to override clone function (or disable cloning altogether) for this component.

fn relationship_accessor() -> Option<ComponentRelationshipAccessor<Self>>

Returns [ComponentRelationshipAccessor] required for working with relationships in dynamic contexts.

fn on_add() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_add [ComponentHook] for this [Component] if one is defined.

fn on_insert() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_insert [ComponentHook] for this [Component] if one is defined.

fn on_discard() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_discard [ComponentHook] for this [Component] if one is defined.

fn on_remove() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_remove [ComponentHook] for this [Component] if one is defined.

fn on_despawn() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_despawn [ComponentHook] for this [Component] if one is defined.

fn map_entities<E>(_this: &mut Self, _mapper: &mut E)

where E: EntityMapper,

Maps the entities on this component using the given [EntityMapper]. This is used to remap entities in contexts like scenes and entity cloning. When deriving [Component], this is populated by annotating fields containing entities with #[entities]

const HAS_SUMMARY_TICK: bool = false

Set this constant to true if the component should track a summary tick.

impl Deref for TextOpacity

type Target = u8

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for TextOpacity

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl PartialEq for TextOpacity

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for TextOpacity