Primitive Type usize [−]

The pointer-sized unsigned integer type.

See also the std::usize module.

Methods

`impl usize`

`const fn min_value() -> usize`

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

`const fn max_value() -> usize`

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

`fn from_str_radix(src: &str, radix: u32) -> Result<usize, ParseIntError>`

Converts a string slice in a given base to an integer.

Leading and trailing whitespace represent an error.

Arguments

src - A string slice
radix - The base to use. Must lie in the range [2 .. 36]

Return value

Err(ParseIntError) if the string did not represent a valid number. Otherwise, Ok(n) where n is the integer represented by src.

`fn count_ones(self) -> u32`

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

Examples

Basic usage:

fn main() { let n = 0b01001100u8; assert_eq!(n.count_ones(), 3); }

let n = 0b01001100u8;

assert_eq!(n.count_ones(), 3);

`fn count_zeros(self) -> u32`

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

Examples

Basic usage:

fn main() { let n = 0b01001100u8; assert_eq!(n.count_zeros(), 5); }

let n = 0b01001100u8;

assert_eq!(n.count_zeros(), 5);

`fn leading_zeros(self) -> u32`

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

Examples

Basic usage:

fn main() { let n = 0b0101000u16; assert_eq!(n.leading_zeros(), 10); }

let n = 0b0101000u16;

assert_eq!(n.leading_zeros(), 10);

`fn trailing_zeros(self) -> u32`

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

Examples

Basic usage:

fn main() { let n = 0b0101000u16; assert_eq!(n.trailing_zeros(), 3); }

let n = 0b0101000u16;

assert_eq!(n.trailing_zeros(), 3);

`fn rotate_left(self, n: u32) -> usize`

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

Examples

Basic usage:

fn main() { let n = 0x0123456789ABCDEFu64; let m = 0x3456789ABCDEF012u64; assert_eq!(n.rotate_left(12), m); }

let n = 0x0123456789ABCDEFu64;
let m = 0x3456789ABCDEF012u64;

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

`fn rotate_right(self, n: u32) -> usize`

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

Examples

Basic usage:

fn main() { let n = 0x0123456789ABCDEFu64; let m = 0xDEF0123456789ABCu64; assert_eq!(n.rotate_right(12), m); }

let n = 0x0123456789ABCDEFu64;
let m = 0xDEF0123456789ABCu64;

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

`fn swap_bytes(self) -> usize`

Reverses the byte order of the integer.

Examples

Basic usage:

fn main() { let n = 0x0123456789ABCDEFu64; let m = 0xEFCDAB8967452301u64; assert_eq!(n.swap_bytes(), m); }

let n = 0x0123456789ABCDEFu64;
let m = 0xEFCDAB8967452301u64;

assert_eq!(n.swap_bytes(), m);

`fn from_be(x: usize) -> usize`

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:

fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "big") { assert_eq!(u64::from_be(n), n) } else { assert_eq!(u64::from_be(n), n.swap_bytes()) } }

let n = 0x0123456789ABCDEFu64;

if cfg!(target_endian = "big") {
    assert_eq!(u64::from_be(n), n)
} else {
    assert_eq!(u64::from_be(n), n.swap_bytes())
}

`fn from_le(x: usize) -> usize`

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:

fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "little") { assert_eq!(u64::from_le(n), n) } else { assert_eq!(u64::from_le(n), n.swap_bytes()) } }

let n = 0x0123456789ABCDEFu64;

if cfg!(target_endian = "little") {
    assert_eq!(u64::from_le(n), n)
} else {
    assert_eq!(u64::from_le(n), n.swap_bytes())
}

`fn to_be(self) -> usize`

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:

fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "big") { assert_eq!(n.to_be(), n) } else { assert_eq!(n.to_be(), n.swap_bytes()) } }

let n = 0x0123456789ABCDEFu64;

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

`fn to_le(self) -> usize`

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:

fn main() { let n = 0x0123456789ABCDEFu64; if cfg!(target_endian = "little") { assert_eq!(n.to_le(), n) } else { assert_eq!(n.to_le(), n.swap_bytes()) } }

let n = 0x0123456789ABCDEFu64;

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

`fn checked_add(self, other: usize) -> Option<usize>`

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

Examples

Basic usage:

fn main() { assert_eq!(5u16.checked_add(65530), Some(65535)); assert_eq!(6u16.checked_add(65530), None); }

assert_eq!(5u16.checked_add(65530), Some(65535));
assert_eq!(6u16.checked_add(65530), None);

`fn checked_sub(self, other: usize) -> Option<usize>`

Checked integer subtraction. Computes self - other, returning None if underflow occurred.

Examples

Basic usage:

fn main() { assert_eq!((-127i8).checked_sub(1), Some(-128)); assert_eq!((-128i8).checked_sub(1), None); }

assert_eq!((-127i8).checked_sub(1), Some(-128));
assert_eq!((-128i8).checked_sub(1), None);

`fn checked_mul(self, other: usize) -> Option<usize>`

Checked integer multiplication. Computes self * other, returning None if underflow or overflow occurred.

Examples

Basic usage:

fn main() { assert_eq!(5u8.checked_mul(51), Some(255)); assert_eq!(5u8.checked_mul(52), None); }

assert_eq!(5u8.checked_mul(51), Some(255));
assert_eq!(5u8.checked_mul(52), None);

`fn checked_div(self, other: usize) -> Option<usize>`

Checked integer division. Computes self / other, returning None if other == 0 or the operation results in underflow or overflow.

Examples

Basic usage:

fn main() { assert_eq!((-127i8).checked_div(-1), Some(127)); assert_eq!((-128i8).checked_div(-1), None); assert_eq!((1i8).checked_div(0), None); }

assert_eq!((-127i8).checked_div(-1), Some(127));
assert_eq!((-128i8).checked_div(-1), None);
assert_eq!((1i8).checked_div(0), None);

`fn saturating_add(self, other: usize) -> usize`

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

Examples

Basic usage:

fn main() { assert_eq!(100i8.saturating_add(1), 101); assert_eq!(100i8.saturating_add(127), 127); }

assert_eq!(100i8.saturating_add(1), 101);
assert_eq!(100i8.saturating_add(127), 127);

`fn saturating_sub(self, other: usize) -> usize`

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

Examples

Basic usage:

fn main() { assert_eq!(100i8.saturating_sub(127), -27); assert_eq!((-100i8).saturating_sub(127), -128); }

assert_eq!(100i8.saturating_sub(127), -27);
assert_eq!((-100i8).saturating_sub(127), -128);

`fn wrapping_add(self, rhs: usize) -> usize`

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

Examples

Basic usage:

fn main() { assert_eq!(100i8.wrapping_add(27), 127); assert_eq!(100i8.wrapping_add(127), -29); }

assert_eq!(100i8.wrapping_add(27), 127);
assert_eq!(100i8.wrapping_add(127), -29);

`fn wrapping_sub(self, rhs: usize) -> usize`

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

Examples

Basic usage:

fn main() { assert_eq!(0i8.wrapping_sub(127), -127); assert_eq!((-2i8).wrapping_sub(127), 127); }

assert_eq!(0i8.wrapping_sub(127), -127);
assert_eq!((-2i8).wrapping_sub(127), 127);

`fn wrapping_mul(self, rhs: usize) -> usize`

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

Examples

Basic usage:

fn main() { assert_eq!(10i8.wrapping_mul(12), 120); assert_eq!(11i8.wrapping_mul(12), -124); }

assert_eq!(10i8.wrapping_mul(12), 120);
assert_eq!(11i8.wrapping_mul(12), -124);

`fn wrapping_div(self, rhs: usize) -> usize`

Wrapping (modular) division. Computes self / other, wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one divides MIN / -1 on a signed type (where MIN is the negative minimal value for the type); this is equivalent to -MIN, a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

Examples

Basic usage:

fn main() { assert_eq!(100u8.wrapping_div(10), 10); assert_eq!((-128i8).wrapping_div(-1), -128); }

assert_eq!(100u8.wrapping_div(10), 10);
assert_eq!((-128i8).wrapping_div(-1), -128);

`fn wrapping_rem(self, rhs: usize) -> usize`

Wrapping (modular) remainder. Computes self % other, wrapping around at the boundary of the type.

Such wrap-around never actually occurs mathematically; implementation artifacts make x % y invalid for MIN / -1 on a signed type (where MIN is the negative minimal value). In such a case, this function returns 0.

Examples

Basic usage:

fn main() { assert_eq!(100i8.wrapping_rem(10), 0); assert_eq!((-128i8).wrapping_rem(-1), 0); }

assert_eq!(100i8.wrapping_rem(10), 0);
assert_eq!((-128i8).wrapping_rem(-1), 0);

`fn wrapping_neg(self) -> usize`

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

The only case where such wrapping can occur is when one negates MIN on a signed type (where MIN is the negative minimal value for the type); this is a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

Examples

Basic usage:

fn main() { assert_eq!(100i8.wrapping_neg(), -100); assert_eq!((-128i8).wrapping_neg(), -128); }

assert_eq!(100i8.wrapping_neg(), -100);
assert_eq!((-128i8).wrapping_neg(), -128);

`fn wrapping_shl(self, rhs: u32) -> usize`

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.

Examples

Basic usage:

fn main() { assert_eq!(1u8.wrapping_shl(7), 128); assert_eq!(1u8.wrapping_shl(8), 1); }

assert_eq!(1u8.wrapping_shl(7), 128);
assert_eq!(1u8.wrapping_shl(8), 1);

`fn wrapping_shr(self, rhs: u32) -> usize`

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.

Examples

Basic usage:

fn main() { assert_eq!(128u8.wrapping_shr(7), 1); assert_eq!(128u8.wrapping_shr(8), 128); }

assert_eq!(128u8.wrapping_shr(7), 1);
assert_eq!(128u8.wrapping_shr(8), 128);

`fn pow(self, exp: u32) -> usize`

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

Examples

Basic usage:

fn main() { assert_eq!(2i32.pow(4), 16); }

assert_eq!(2i32.pow(4), 16);

`fn is_power_of_two(self) -> bool`

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

Examples

Basic usage:

fn main() { assert!(16u8.is_power_of_two()); assert!(!10u8.is_power_of_two()); }

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

`fn next_power_of_two(self) -> usize`

Returns the smallest power of two greater than or equal to self. Unspecified behavior on overflow.

Examples

Basic usage:

fn main() { assert_eq!(2u8.next_power_of_two(), 2); assert_eq!(3u8.next_power_of_two(), 4); }

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

`fn checked_next_power_of_two(self) -> Option<usize>`

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, None is returned, otherwise the power of two is wrapped in Some.

Examples

Basic usage:

fn main() { assert_eq!(2u8.checked_next_power_of_two(), Some(2)); assert_eq!(3u8.checked_next_power_of_two(), Some(4)); assert_eq!(200u8.checked_next_power_of_two(), None); }

assert_eq!(2u8.checked_next_power_of_two(), Some(2));
assert_eq!(3u8.checked_next_power_of_two(), Some(4));
assert_eq!(200u8.checked_next_power_of_two(), None);

Trait Implementations

`impl OverflowingOps for usize`

`fn overflowing_add(self, rhs: usize) -> (usize, bool)`

`fn overflowing_sub(self, rhs: usize) -> (usize, bool)`

`fn overflowing_mul(self, rhs: usize) -> (usize, bool)`

`fn overflowing_div(self, rhs: usize) -> (usize, bool)`

`fn overflowing_rem(self, rhs: usize) -> (usize, bool)`

`fn overflowing_neg(self) -> (usize, bool)`

`fn overflowing_shl(self, rhs: u32) -> (usize, bool)`

`fn overflowing_shr(self, rhs: u32) -> (usize, bool)`

`impl Zero for usize`

`fn zero() -> usize`

`impl One for usize`

`fn one() -> usize`

`impl FromStr for usize`

`type Err = ParseIntError`

`fn from_str(src: &str) -> Result<usize, ParseIntError>`

`impl From<u8> for usize`

`fn from(small: u8) -> usize`

`impl Zeroable for usize`

`impl Add<usize> for usize`

`type Output = usize`

`fn add(self, other: usize) -> usize`

`impl<'a> Add<usize> for &'a usize`

`type Output = usize::Output`

`fn add(self, other: usize) -> usize::Output`

`impl<'a> Add<&'a usize> for usize`

`type Output = usize::Output`

`fn add(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> Add<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn add(self, other: &'a usize) -> usize::Output`

`impl Sub<usize> for usize`

`type Output = usize`

`fn sub(self, other: usize) -> usize`

`impl<'a> Sub<usize> for &'a usize`

`type Output = usize::Output`

`fn sub(self, other: usize) -> usize::Output`

`impl<'a> Sub<&'a usize> for usize`

`type Output = usize::Output`

`fn sub(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> Sub<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn sub(self, other: &'a usize) -> usize::Output`

`impl Mul<usize> for usize`

`type Output = usize`

`fn mul(self, other: usize) -> usize`

`impl<'a> Mul<usize> for &'a usize`

`type Output = usize::Output`

`fn mul(self, other: usize) -> usize::Output`

`impl<'a> Mul<&'a usize> for usize`

`type Output = usize::Output`

`fn mul(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> Mul<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn mul(self, other: &'a usize) -> usize::Output`

`impl Div<usize> for usize`

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

`type Output = usize`

`fn div(self, other: usize) -> usize`

`impl<'a> Div<usize> for &'a usize`

`type Output = usize::Output`

`fn div(self, other: usize) -> usize::Output`

`impl<'a> Div<&'a usize> for usize`

`type Output = usize::Output`

`fn div(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> Div<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn div(self, other: &'a usize) -> usize::Output`

`impl Rem<usize> for usize`

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

`type Output = usize`

`fn rem(self, other: usize) -> usize`

`impl<'a> Rem<usize> for &'a usize`

`type Output = usize::Output`

`fn rem(self, other: usize) -> usize::Output`

`impl<'a> Rem<&'a usize> for usize`

`type Output = usize::Output`

`fn rem(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> Rem<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn rem(self, other: &'a usize) -> usize::Output`

`impl Not for usize`

`type Output = usize`

`fn not(self) -> usize`

`impl<'a> Not for &'a usize`

`type Output = usize::Output`

`fn not(self) -> usize::Output`

`impl BitAnd<usize> for usize`

`type Output = usize`

`fn bitand(self, rhs: usize) -> usize`

`impl<'a> BitAnd<usize> for &'a usize`

`type Output = usize::Output`

`fn bitand(self, other: usize) -> usize::Output`

`impl<'a> BitAnd<&'a usize> for usize`

`type Output = usize::Output`

`fn bitand(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> BitAnd<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn bitand(self, other: &'a usize) -> usize::Output`

`impl BitOr<usize> for usize`

`type Output = usize`

`fn bitor(self, rhs: usize) -> usize`

`impl<'a> BitOr<usize> for &'a usize`

`type Output = usize::Output`

`fn bitor(self, other: usize) -> usize::Output`

`impl<'a> BitOr<&'a usize> for usize`

`type Output = usize::Output`

`fn bitor(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> BitOr<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn bitor(self, other: &'a usize) -> usize::Output`

`impl BitXor<usize> for usize`

`type Output = usize`

`fn bitxor(self, other: usize) -> usize`

`impl<'a> BitXor<usize> for &'a usize`

`type Output = usize::Output`

`fn bitxor(self, other: usize) -> usize::Output`

`impl<'a> BitXor<&'a usize> for usize`

`type Output = usize::Output`

`fn bitxor(self, other: &'a usize) -> usize::Output`

`impl<'a, 'b> BitXor<&'a usize> for &'b usize`

`type Output = usize::Output`

`fn bitxor(self, other: &'a usize) -> usize::Output`

`impl Shl<u8> for usize`

`type Output = usize`

`fn shl(self, other: u8) -> usize`

`impl<'a> Shl<u8> for &'a usize`

`type Output = usize::Output`