usize - Rust (original) (raw)

Primitive Type usize

1.0.0

Expand description

The pointer-sized unsigned integer type.

The size of this primitive is how many bytes it takes to reference any location in memory. For example, on a 32 bit target, this is 4 bytes and on a 64 bit target, this is 8 bytes.

Source §

1.43.0 · Source

The smallest value that can be represented by this integer type.

§Examples

Basic usage:

assert_eq!(usize::MIN, 0);

1.43.0 · Source

The largest value that can be represented by this integer type (264 − 1 on 64-bit targets).

§Examples

Basic usage:

assert_eq!(usize::MAX, 18446744073709551615);

1.53.0 · Source

The size of this integer type in bits.

§Examples

assert_eq!(usize::BITS, 64);

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

let n = 0b01001100usize;
assert_eq!(n.count_ones(), 3);

let max = usize::MAX;
assert_eq!(max.count_ones(), 64);

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

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

let zero = 0usize;
assert_eq!(zero.count_zeros(), 64);

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

1.0.0 (const: 1.32.0) · Source

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 theilog2 function which returns a consistent number, even if the type widens.

§Examples

Basic usage:

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

let zero = 0usize;
assert_eq!(zero.leading_zeros(), 64);

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

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

let n = 0b0101000usize;
assert_eq!(n.trailing_zeros(), 3);

let zero = 0usize;
assert_eq!(zero.trailing_zeros(), 64);

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

1.46.0 (const: 1.46.0) · Source

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

§Examples

Basic usage:

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

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

let max = usize::MAX;
assert_eq!(max.leading_ones(), 64);

1.46.0 (const: 1.46.0) · Source

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

§Examples

Basic usage:

let n = 0b1010111usize;
assert_eq!(n.trailing_ones(), 3);

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

let max = usize::MAX;
assert_eq!(max.trailing_ones(), 64);

Source

🔬This is a nightly-only experimental API. (integer_sign_cast #125882)

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

Basic usage:

#![feature(integer_sign_cast)]

let n = usize::MAX;

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

1.0.0 (const: 1.32.0) · Source

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

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

§Examples

Basic usage:

let n = 0xaa00000000006e1usize;
let m = 0x6e10aa;

assert_eq!(n.rotate_left(12), m);

1.0.0 (const: 1.32.0) · Source

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

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

§Examples

Basic usage:

let n = 0x6e10aausize;
let m = 0xaa00000000006e1;

assert_eq!(n.rotate_right(12), m);

1.0.0 (const: 1.32.0) · Source

Reverses the byte order of the integer.

§Examples

Basic usage:

let n = 0x1234567890123456usize;
let m = n.swap_bytes();

assert_eq!(m, 0x5634129078563412);

1.37.0 (const: 1.37.0) · Source

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

Basic usage:

let n = 0x1234567890123456usize;
let m = n.reverse_bits();

assert_eq!(m, 0x6a2c48091e6a2c48);
assert_eq!(0, 0usize.reverse_bits());

1.0.0 (const: 1.32.0) · Source

Converts an integer from big endian to the target’s endianness.

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

§Examples

Basic usage:

let n = 0x1Ausize;

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

1.0.0 (const: 1.32.0) · Source

Converts an integer from little endian to the target’s endianness.

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

§Examples

Basic usage:

let n = 0x1Ausize;

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

1.0.0 (const: 1.32.0) · Source

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

Basic usage:

let n = 0x1Ausize;

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

1.0.0 (const: 1.32.0) · Source

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

Basic usage:

let n = 0x1Ausize;

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

1.0.0 (const: 1.47.0) · Source

Checked integer addition. Computes self + rhs, returning Noneif overflow occurred.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!((usize::MAX - 2).strict_add(1), usize::MAX - 1);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = (usize::MAX - 2).strict_add(3);

1.79.0 (const: 1.79.0) · Source

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

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

If you’re just trying to avoid the panic in debug mode, then do notuse this. Instead, you’re looking for wrapping_add.

§Safety

This results in undefined behavior whenself + rhs > usize::MAX or self + rhs < usize::MIN, i.e. when checked_add would return None.

1.66.0 (const: 1.66.0) · Source

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

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(1usize.strict_add_signed(2), 3);

The following panic because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 1usize.strict_add_signed(-2);

ⓘ

#![feature(strict_overflow_ops)]
let _ = (usize::MAX - 2).strict_add_signed(3);

1.0.0 (const: 1.47.0) · Source

Checked integer subtraction. Computes self - rhs, returningNone if overflow occurred.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(1usize.strict_sub(1), 0);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 0usize.strict_sub(1);

1.79.0 (const: 1.79.0) · Source

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

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

If you’re just trying to avoid the panic in debug mode, then do notuse 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 whenself - rhs > usize::MAX or self - rhs < usize::MIN, i.e. when checked_sub would return None.

Source

🔬This is a nightly-only experimental API. (mixed_integer_ops_unsigned_sub #126043)

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

§Examples

Basic usage:

#![feature(mixed_integer_ops_unsigned_sub)]
assert_eq!(1usize.checked_sub_signed(2), None);
assert_eq!(1usize.checked_sub_signed(-2), Some(3));
assert_eq!((usize::MAX - 2).checked_sub_signed(-4), None);

Source

🔬This is a nightly-only experimental API. (unsigned_signed_diff #126041)

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

§Examples

Basic usage:

#![feature(unsigned_signed_diff)]
assert_eq!(10usize.checked_signed_diff(2), Some(8));
assert_eq!(2usize.checked_signed_diff(10), Some(-8));
assert_eq!(usize::MAX.checked_signed_diff(isize::MAX as usize), None);
assert_eq!((isize::MAX as usize).checked_signed_diff(usize::MAX), Some(isize::MIN));
assert_eq!((isize::MAX as usize + 1).checked_signed_diff(0), None);
assert_eq!(usize::MAX.checked_signed_diff(usize::MAX), Some(0));

1.0.0 (const: 1.47.0) · Source

Checked integer multiplication. Computes self * rhs, returningNone if overflow occurred.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(5usize.strict_mul(1), 5);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = usize::MAX.strict_mul(2);

1.79.0 (const: 1.79.0) · Source

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

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

If you’re just trying to avoid the panic in debug mode, then do notuse this. Instead, you’re looking for wrapping_mul.

§Safety

This results in undefined behavior whenself * rhs > usize::MAX or self * rhs < usize::MIN, i.e. when checked_mul would return None.

1.0.0 (const: 1.52.0) · Source

Checked integer division. Computes self / rhs, returning Noneif rhs == 0.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(100usize.strict_div(10), 10);

The following panics because of division by zero:

ⓘ

#![feature(strict_overflow_ops)]
let _ = (1usize).strict_div(0);

1.38.0 (const: 1.52.0) · Source

Checked Euclidean division. Computes self.div_euclid(rhs), returning Noneif rhs == 0.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(100usize.strict_div_euclid(10), 10);

The following panics because of division by zero:

ⓘ

#![feature(strict_overflow_ops)]
let _ = (1usize).strict_div_euclid(0);

1.7.0 (const: 1.52.0) · Source

Checked integer remainder. Computes self % rhs, returning Noneif rhs == 0.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(100usize.strict_rem(10), 0);

The following panics because of division by zero:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 5usize.strict_rem(0);

1.38.0 (const: 1.52.0) · Source

Checked Euclidean modulo. Computes self.rem_euclid(rhs), returning Noneif rhs == 0.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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 toself.strict_rem(rhs).

§Panics

This function will panic if rhs is zero.

§Examples

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(100usize.strict_rem_euclid(10), 0);

The following panics because of division by zero:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 5usize.strict_rem_euclid(0);

Source

🔬This is a nightly-only experimental API. (disjoint_bitor #135758)

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_usize.unchecked_disjoint_bitor(4), 5);
}

§Safety

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

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

1.67.0 (const: 1.67.0) · Source

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 ilog10can 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!(5usize.ilog(5), 1);

1.67.0 (const: 1.67.0) · Source

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

§Panics

This function will panic if self is zero.

§Examples

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

1.67.0 (const: 1.67.0) · Source

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

§Panics

This function will panic if self is zero.

§Example

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

1.67.0 (const: 1.67.0) · Source

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, andchecked_ilog10 can produce results more efficiently for base 10.

§Examples

assert_eq!(5usize.checked_ilog(5), Some(1));

1.67.0 (const: 1.67.0) · Source

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

Returns None if the number is zero.

§Examples

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

1.67.0 (const: 1.67.0) · Source

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

Returns None if the number is zero.

§Examples

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

1.7.0 (const: 1.47.0) · Source

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

Note that negating any positive integer will overflow.

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(0usize.strict_neg(), 0);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 1usize.strict_neg();

1.7.0 (const: 1.47.0) · Source

Checked shift left. Computes self << rhs, returning Noneif rhs is larger than or equal to the number of bits in self.

§Examples

Basic usage:

assert_eq!(0x1usize.checked_shl(4), Some(0x10));
assert_eq!(0x10usize.checked_shl(129), None);
assert_eq!(0x10usize.checked_shl(63), Some(0));

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(0x1usize.strict_shl(4), 0x10);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 0x10usize.strict_shl(129);

Source

🔬This is a nightly-only experimental API. (unchecked_shifts #85122)

Unchecked shift left. Computes self << rhs, assuming thatrhs 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.

Source

🔬This is a nightly-only experimental API. (unbounded_shifts #129375)

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

Basic usage:

#![feature(unbounded_shifts)]
assert_eq!(0x1usize.unbounded_shl(4), 0x10);
assert_eq!(0x1usize.unbounded_shl(129), 0);

1.7.0 (const: 1.47.0) · Source

Checked shift right. Computes self >> rhs, returning Noneif rhs is larger than or equal to the number of bits in self.

§Examples

Basic usage:

assert_eq!(0x10usize.checked_shr(4), Some(0x1));
assert_eq!(0x10usize.checked_shr(129), None);

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

Strict shift right. Computes self >> rhs, panicking 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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(0x10usize.strict_shr(4), 0x1);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = 0x10usize.strict_shr(129);

Source

🔬This is a nightly-only experimental API. (unchecked_shifts #85122)

Unchecked shift right. Computes self >> rhs, assuming thatrhs 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.

Source

🔬This is a nightly-only experimental API. (unbounded_shifts #129375)

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

Basic usage:

#![feature(unbounded_shifts)]
assert_eq!(0x10usize.unbounded_shr(4), 0x1);
assert_eq!(0x10usize.unbounded_shr(129), 0);

1.34.0 (const: 1.50.0) · Source

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

§Examples

Basic usage:

assert_eq!(2usize.checked_pow(5), Some(32));
assert_eq!(usize::MAX.checked_pow(2), None);

Source

🔬This is a nightly-only experimental API. (strict_overflow_ops #118260)

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

Basic usage:

#![feature(strict_overflow_ops)]
assert_eq!(2usize.strict_pow(5), 32);

The following panics because of overflow:

ⓘ

#![feature(strict_overflow_ops)]
let _ = usize::MAX.strict_pow(2);

1.0.0 (const: 1.47.0) · Source

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

§Examples

Basic usage:

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

1.66.0 (const: 1.66.0) · Source

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

§Examples

Basic usage:

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

1.0.0 (const: 1.47.0) · Source

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

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (mixed_integer_ops_unsigned_sub #126043)

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

§Examples

Basic usage:

#![feature(mixed_integer_ops_unsigned_sub)]
assert_eq!(1usize.saturating_sub_signed(2), 0);
assert_eq!(1usize.saturating_sub_signed(-2), 3);
assert_eq!((usize::MAX - 2).saturating_sub_signed(-4), usize::MAX);

1.7.0 (const: 1.47.0) · Source

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

§Examples

Basic usage:

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

1.58.0 (const: 1.58.0) · Source

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

§Panics

This function will panic if rhs is zero.

§Examples

Basic usage:

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

1.34.0 (const: 1.50.0) · Source

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

§Examples

Basic usage:

assert_eq!(4usize.saturating_pow(3), 64);
assert_eq!(usize::MAX.saturating_pow(2), usize::MAX);

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

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

1.66.0 (const: 1.66.0) · Source

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

§Examples

Basic usage:

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

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (mixed_integer_ops_unsigned_sub #126043)

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

§Examples

Basic usage:

#![feature(mixed_integer_ops_unsigned_sub)]
assert_eq!(1usize.wrapping_sub_signed(2), usize::MAX);
assert_eq!(1usize.wrapping_sub_signed(-2), 3);
assert_eq!((usize::MAX - 2).wrapping_sub_signed(-4), 1);

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

Please note that this example is shared between integer types. Which explains why u8 is used here.

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

1.2.0 (const: 1.52.0) · Source

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

Basic usage:

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

1.38.0 (const: 1.52.0) · Source

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

Basic usage:

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

1.2.0 (const: 1.52.0) · Source

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

Basic usage:

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

1.38.0 (const: 1.52.0) · Source

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 toself.wrapping_rem(rhs).

§Panics

This function will panic if rhs is zero.

§Examples

Basic usage:

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

1.2.0 (const: 1.32.0) · Source

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) whereMAX is the corresponding signed type’s maximum.

§Examples

Basic usage:

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

1.2.0 (const: 1.32.0) · Source

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.

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

Basic usage:

assert_eq!(1usize.wrapping_shl(7), 128);
assert_eq!(1usize.wrapping_shl(128), 1);

1.2.0 (const: 1.32.0) · Source

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.

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

Basic usage:

assert_eq!(128usize.wrapping_shr(7), 1);
assert_eq!(128usize.wrapping_shr(128), 128);

1.34.0 (const: 1.50.0) · Source

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

§Examples

Basic usage:

assert_eq!(3usize.wrapping_pow(5), 243);
assert_eq!(3u8.wrapping_pow(6), 217);

1.7.0 (const: 1.32.0) · Source

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

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

Calculates self + rhs + carry and returns a tuple containing the sum and the output carry.

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 64-bit “full adder”, in the electronics sense.

If the input carry is false, this method is equivalent tooverflowing_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

#![feature(bigint_helper_methods)]

//    3  MAX    (a = 3 × 2^64 + 2^64 - 1)
// +  5    7    (b = 5 × 2^64 + 7)
// ---------
//    9    6    (sum = 9 × 2^64 + 6)

let (a1, a0): (usize, usize) = (3, usize::MAX);
let (b1, b0): (usize, usize) = (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));

1.66.0 (const: 1.66.0) · Source

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

Basic usage:

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

1.7.0 (const: 1.32.0) · Source

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

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

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

#![feature(bigint_helper_methods)]

//    9    6    (a = 9 × 2^64 + 6)
// -  5    7    (b = 5 × 2^64 + 7)
// ---------
//    3  MAX    (diff = 3 × 2^64 + 2^64 - 1)

let (a1, a0): (usize, usize) = (9, 6);
let (b1, b0): (usize, usize) = (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, usize::MAX));

Source

🔬This is a nightly-only experimental API. (mixed_integer_ops_unsigned_sub #126043)

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

Basic usage:

#![feature(mixed_integer_ops_unsigned_sub)]
assert_eq!(1usize.overflowing_sub_signed(2), (usize::MAX, true));
assert_eq!(1usize.overflowing_sub_signed(-2), (3, false));
assert_eq!((usize::MAX - 2).overflowing_sub_signed(-4), (1, true));

1.60.0 (const: 1.60.0) · Source

Computes the absolute difference between self and other.

§Examples

Basic usage:

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

1.7.0 (const: 1.32.0) · Source

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.

§Examples

Basic usage:

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

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

Source

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

Calculates the complete product self * rhs 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.

If you also need to add a carry to the wide result, then you wantSelf::carrying_mul instead.

§Examples

Basic usage:

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

#![feature(bigint_helper_methods)]
assert_eq!(5u32.widening_mul(2), (10, 0));
assert_eq!(1_000_000_000u32.widening_mul(10), (1410065408, 2));

Source

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

Calculates the “full multiplication” self * rhs + carrywithout 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 don’t need the carry, then you can use Self::widening_mul instead.

§Examples

Basic usage:

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

#![feature(bigint_helper_methods)]
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!(usize::MAX.carrying_mul(usize::MAX, usize::MAX), (0, usize::MAX));

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

#![feature(bigint_helper_methods)]
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(bigint_helper_methods)]
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 andwrapping_add methods:

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

Source

🔬This is a nightly-only experimental API. (bigint_helper_methods #85532)

Calculates the “full multiplication” self * rhs + carry1 + carry2without 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.

If you don’t need either carry, then you can use Self::widening_mul instead, and if you only need one carry, then you can use Self::carrying_mul instead.

§Examples

Basic usage:

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

#![feature(bigint_helper_methods)]
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!(usize::MAX.carrying_mul_add(usize::MAX, usize::MAX, usize::MAX), (usize::MAX, usize::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.

#![feature(bigint_helper_methods)]

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)
);

1.7.0 (const: 1.52.0) · Source

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 alwaysfalse.

§Panics

This function will panic if rhs is zero.

§Examples

Basic usage:

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

1.38.0 (const: 1.52.0) · Source

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 alwaysfalse. 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

Basic usage:

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

1.7.0 (const: 1.52.0) · Source

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

Basic usage:

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

1.38.0 (const: 1.52.0) · Source

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

Basic usage:

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

1.7.0 (const: 1.32.0) · Source

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

Basic usage:

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

1.7.0 (const: 1.32.0) · Source

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

Basic usage:

assert_eq!(0x1usize.overflowing_shl(4), (0x10, false));
assert_eq!(0x1usize.overflowing_shl(132), (0x10, true));
assert_eq!(0x10usize.overflowing_shl(63), (0, false));

1.7.0 (const: 1.32.0) · Source

Shifts self right by rhs bits.

§Examples

Basic usage:

assert_eq!(0x10usize.overflowing_shr(4), (0x1, false));
assert_eq!(0x10usize.overflowing_shr(132), (0x1, true));

1.34.0 (const: 1.50.0) · Source

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

Basic usage:

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

1.0.0 (const: 1.50.0) · Source

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

§Examples

Basic usage:

assert_eq!(2usize.pow(5), 32);

1.84.0 (const: 1.84.0) · Source

Returns the square root of the number, rounded down.

§Examples

Basic usage:

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

1.38.0 (const: 1.52.0) · Source

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

Basic usage:

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

1.38.0 (const: 1.52.0) · Source

Calculates the least remainder of self (mod 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

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (int_roundings #88581)

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

Basic usage:

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

1.73.0 (const: 1.73.0) · Source

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

§Panics

This function will panic if rhs is zero.

§Examples

Basic usage:

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

1.73.0 (const: 1.73.0) · Source

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

Basic usage:

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

1.73.0 (const: 1.73.0) · Source

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

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (unsigned_is_multiple_of #128101)

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

Basic usage:

#![feature(unsigned_is_multiple_of)]
assert!(6_usize.is_multiple_of(2));
assert!(!5_usize.is_multiple_of(2));

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

1.0.0 (const: 1.32.0) · Source

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

§Examples

Basic usage:

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

1.0.0 (const: 1.50.0) · Source

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

When return value overflows (i.e., self > (1 << (N-1)) for typeuN), 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

Basic usage:

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

1.0.0 (const: 1.50.0) · Source

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

Basic usage:

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

Source

🔬This is a nightly-only experimental API. (wrapping_next_power_of_two #32463)

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

Basic usage:

#![feature(wrapping_next_power_of_two)]

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

1.32.0 (const: 1.44.0) · Source

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

Note: This function returns an array of length 2, 4 or 8 bytes depending on the target pointer size.

§Examples

let bytes = 0x1234567890123456usize.to_be_bytes();
assert_eq!(bytes, [0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]);

1.32.0 (const: 1.44.0) · Source

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

Note: This function returns an array of length 2, 4 or 8 bytes depending on the target pointer size.

§Examples

let bytes = 0x1234567890123456usize.to_le_bytes();
assert_eq!(bytes, [0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]);

1.32.0 (const: 1.44.0) · Source

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 returns an array of length 2, 4 or 8 bytes depending on the target pointer size.

§Examples

let bytes = 0x1234567890123456usize.to_ne_bytes();
assert_eq!(
    bytes,
    if cfg!(target_endian = "big") {
        [0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]
    } else {
        [0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]
    }
);

1.32.0 (const: 1.44.0) · Source

Creates a native endian integer value from its representation as a byte array in big endian.

Note: This function takes an array of length 2, 4 or 8 bytes depending on the target pointer size.

§Examples

let value = usize::from_be_bytes([0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]);
assert_eq!(value, 0x1234567890123456);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_be_usize(input: &mut &[u8]) -> usize {
    let (int_bytes, rest) = input.split_at(std::mem::size_of::<usize>());
    *input = rest;
    usize::from_be_bytes(int_bytes.try_into().unwrap())
}

1.32.0 (const: 1.44.0) · Source

Creates a native endian integer value from its representation as a byte array in little endian.

Note: This function takes an array of length 2, 4 or 8 bytes depending on the target pointer size.

§Examples

let value = usize::from_le_bytes([0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]);
assert_eq!(value, 0x1234567890123456);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_le_usize(input: &mut &[u8]) -> usize {
    let (int_bytes, rest) = input.split_at(std::mem::size_of::<usize>());
    *input = rest;
    usize::from_le_bytes(int_bytes.try_into().unwrap())
}

1.32.0 (const: 1.44.0) · Source

Creates a native endian integer value from its memory representation as a byte array in native endianness.

As the target platform’s native endianness is used, portable code likely wants to use from_be_bytes or from_le_bytes, as appropriate instead.

Note: This function takes an array of length 2, 4 or 8 bytes depending on the target pointer size.

§Examples

let value = usize::from_ne_bytes(if cfg!(target_endian = "big") {
    [0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]
} else {
    [0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]
});
assert_eq!(value, 0x1234567890123456);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_ne_usize(input: &mut &[u8]) -> usize {
    let (int_bytes, rest) = input.split_at(std::mem::size_of::<usize>());
    *input = rest;
    usize::from_ne_bytes(int_bytes.try_into().unwrap())
}

1.0.0 (const: 1.32.0) · Source

👎Deprecating in a future version: replaced by the MIN associated constant on this type

New code should prefer to useusize::MIN instead.

Returns the smallest value that can be represented by this integer type.

1.0.0 (const: 1.32.0) · Source

👎Deprecating in a future version: replaced by the MAX associated constant on this type

New code should prefer to useusize::MAX instead.

Returns the largest value that can be represented by this integer type.

1.85.0 (const: 1.85.0) · Source

Calculates the middle point of 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!(0usize.midpoint(4), 2);
assert_eq!(1usize.midpoint(4), 2);

Source §

1.0.0 (const: 1.82.0) · Source

Parses an integer from a string slice with digits in a given base.

The string is expected to be an optional+sign followed by only digits. Leading and trailing non-digit characters (including whitespace) represent an error. Underscores (which are accepted in Rust literals) also represent an error.

Digits are a subset of these characters, depending on radix:

0-9
a-z
A-Z

§Panics

This function panics if radix is not in the range from 2 to 36.

§Examples

Basic usage:

assert_eq!(usize::from_str_radix("A", 16), Ok(10));

Trailing space returns error:

assert!(usize::from_str_radix("1 ", 10).is_err());

Source

🔬This is a nightly-only experimental API. (int_from_ascii #134821)

Parses an integer from an ASCII-byte slice with decimal digits.

The characters are expected to be an optional+sign followed by only digits. Leading and trailing non-digit characters (including whitespace) represent an error. Underscores (which are accepted in Rust literals) also represent an error.

§Examples

Basic usage:

#![feature(int_from_ascii)]

assert_eq!(usize::from_ascii(b"+10"), Ok(10));

Trailing space returns error:

assert!(usize::from_ascii(b"1 ").is_err());

Source

🔬This is a nightly-only experimental API. (int_from_ascii #134821)

Parses an integer from an ASCII-byte slice with digits in a given base.

Digits are a subset of these characters, depending on radix:

0-9
a-z
A-Z

§Panics

This function panics if radix is not in the range from 2 to 36.

§Examples

Basic usage:

#![feature(int_from_ascii)]

assert_eq!(usize::from_ascii_radix(b"A", 16), Ok(10));

Trailing space returns error:

assert!(usize::from_ascii_radix(b"1 ", 10).is_err());

1.0.0 · Source §

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The resulting type after applying the + operator.

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1.0.0 · Source §

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The resulting type after applying the + operator.

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1.0.0 · Source §

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The resulting type after applying the + operator.

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1.0.0 · Source §

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The resulting type after applying the + operator.

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The resulting type after applying the & operator.

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1.0.0 · Source §

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The resulting type after applying the & operator.

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1.0.0 · Source §

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The resulting type after applying the & operator.

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1.0.0 · Source §

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The resulting type after applying the & operator.

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The resulting type after applying the | operator.

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1.0.0 · Source §

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The resulting type after applying the | operator.

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1.0.0 · Source §

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The resulting type after applying the | operator.

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1.0.0 · Source §

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The resulting type after applying the | operator.

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1.22.0 · Source §

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The resulting type after applying the ^ operator.

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1.0.0 · Source §

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The resulting type after applying the ^ operator.

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1.0.0 · Source §

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The resulting type after applying the ^ operator.

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1.0.0 · Source §

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The resulting type after applying the ^ operator.

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1.22.0 · Source §

1.74.0 · Source §

1.60.0 · Source §

1.8.0 · Source §

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

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

1.0.0 · Source §

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Returns the default value of 0

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

See super::disjoint_bitor; we just need the trait indirection to handle different types since calling intrinsics with generics doesn’t work.

1.0.0 · Source §

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The resulting type after applying the / operator.

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1.0.0 · Source §

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The resulting type after applying the / operator.

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1.51.0 · Source §

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Same as self / other.get(), but because other is a NonZero<_>, there’s never a runtime check for division-by-zero.

This operation rounds towards zero, truncating any fractional part of the exact result, and cannot panic.

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The resulting type after applying the / operator.

1.0.0 · Source §

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The resulting type after applying the / operator.

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1.0.0 · Source §

This operation rounds towards zero, truncating any fractional part of the exact result.

§Panics

This operation will panic if other == 0.

Source §

The resulting type after applying the / operator.

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1.22.0 · Source §

1.79.0 · Source §

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Same as self /= other.get(), but because other is a NonZero<_>, there’s never a runtime check for division-by-zero.

This operation rounds towards zero, truncating any fractional part of the exact result, and cannot panic.

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Converts to this type from the input type.

1.28.0 · Source §

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Converts a bool to usize losslessly. The resulting value is 0 for false and 1 for true values.

§Examples

assert_eq!(usize::from(true), 1);
assert_eq!(usize::from(false), 0);

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1.23.0 · Source §

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Converts an usize into an AtomicUsize.

1.0.0 · Source §

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Parses an integer from a string slice with decimal digits.

§Examples

Basic usage:

use std::str::FromStr;

assert_eq!(usize::from_str("+10"), Ok(10));

Trailing space returns error:

assert!(usize::from_str("1 ").is_err());

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The associated error which can be returned from parsing.

Source §

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

Returns true if self is in bounds for len slice elements.

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

Returns true if self overlaps with other. Read more

1.0.0 · Source §

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The returned type after indexing.

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Performs the indexing (container[index]) operation. Read more

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The returned type after indexing.

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Performs the indexing (container[index]) operation. Read more

1.0.0 · Source §

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The returned type after indexing.

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Performs the indexing (container[index]) operation. Read more

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1.0.0 · Source §

1.42.0 · Source §

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The resulting type after applying the * operator.

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1.0.0 · Source §

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The resulting type after applying the * operator.

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1.0.0 · Source §

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The resulting type after applying the * operator.

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1.0.0 · Source §

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The resulting type after applying the * operator.

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Tests for self and other values to be equal, and is used by ==.

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Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

1.0.0 · Source §

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This method returns an ordering between self and other values if one exists. Read more

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Tests less than (for self and other) and is used by the < operator. Read more

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Tests less than or equal to (for self and other) and is used by the<= operator. Read more

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Tests greater than or equal to (for self and other) and is used by the >= operator. Read more

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Tests greater than (for self and other) and is used by the >operator. Read more

1.12.0 · Source §

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Takes an iterator and generates Self from the elements by multiplying the items.

1.12.0 · Source §

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Takes an iterator and generates Self from the elements by multiplying the items.

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🔬This is a nightly-only experimental API. (random #130703)

Generates a random value.

Warning: Be careful when manipulating the resulting value! This method samples according to a uniform distribution, so a value of 1 is just as likely as MAX. By using modulo operations, some values can become more likely than others. Use audited crates when in doubt.

1.0.0 · Source §

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The resulting type after applying the % operator.

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1.0.0 · Source §

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The resulting type after applying the % operator.

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1.51.0 · Source §

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This operation satisfies n % d == n - (n / d) * d, and cannot panic.

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The resulting type after applying the % operator.

1.0.0 · Source §

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The resulting type after applying the % operator.

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1.0.0 · Source §

This operation satisfies n % d == n - (n / d) * d. The result has the same sign as the left operand.

§Panics

This operation will panic if other == 0.

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The resulting type after applying the % operator.

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1.22.0 · Source §

1.79.0 · Source §

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This operation satisfies n % d == n - (n / d) * d, and cannot panic.

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1.0.0 · Source §

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