# Primitive Type usize1.0.0[−]

## 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.

## Implementations

## This is supported on **64-bit** only.

**64-bit**only.

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.

##### 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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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.

##### 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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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

The string is expected to be an optional `+`

sign
followed by digits.
Leading and trailing whitespace 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));`

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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());
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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())
}
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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())
}
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

This is supported on **64-bit** only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

**64-bit**only.

Unchecked integer addition. Computes `self + rhs`

, assuming overflow
cannot occur.

##### Safety

This results in undefined behavior when
`self + rhs > usize::MAX`

or `self + rhs < usize::MIN`

,
i.e. when `checked_add`

would return `None`

.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

This is supported on **64-bit** only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

**64-bit**only.

Unchecked integer subtraction. Computes `self - rhs`

, assuming overflow
cannot occur.

##### Safety

This results in undefined behavior when
`self - rhs > usize::MAX`

or `self - rhs < usize::MIN`

,
i.e. when `checked_sub`

would return `None`

.

## This is supported on **64-bit** only.

**64-bit**only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

This is supported on **64-bit** only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

**64-bit**only.

Unchecked integer multiplication. Computes `self * rhs`

, assuming overflow
cannot occur.

##### Safety

This results in undefined behavior when
`self * rhs > usize::MAX`

or `self * rhs < usize::MIN`

,
i.e. when `checked_mul`

would return `None`

.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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

This method might not be optimized owing to implementation details;
`log2`

can produce results more efficiently for base 2, and `log10`

can produce results more efficiently for base 10.

##### Panics

When the number is negative, zero, or if the base is not at least 2; it panics in debug mode and the return value is 0 in release mode.

##### Examples

```
#![feature(int_log)]
assert_eq!(5usize.log(5), 1);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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_log2`

can produce results more efficiently for base 2, and
`checked_log10`

can produce results more efficiently for base 10.

##### Examples

```
#![feature(int_log)]
assert_eq!(5usize.checked_log(5), Some(1));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

This is supported on **64-bit** only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

**64-bit**only.

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`

.

## This is supported on **64-bit** only.

**64-bit**only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

This is supported on **64-bit** only.

## 🔬 This is a nightly-only experimental API. (`unchecked_math`

#85122)

niche optimization path

**64-bit**only.

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`

.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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.

##### Examples

Basic usage:

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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)`

.

##### Examples

Basic usage:

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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.

##### Examples

Basic usage:

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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)`

.

##### Examples

Basic usage:

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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

Basic usage:

Please note that this example is shared between integer types.
Which explains why `i8`

is used here.

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Calculates `self + rhs + carry`

without the ability to overflow.

Performs “ternary addition” which takes in an extra bit to add, and may return an additional bit of overflow. This allows for chaining together multiple additions to create “big integers” which represent larger values.

##### Examples

Basic usage

```
#![feature(bigint_helper_methods)]
assert_eq!(5usize.carrying_add(2, false), (7, false));
assert_eq!(5usize.carrying_add(2, true), (8, false));
assert_eq!(usize::MAX.carrying_add(1, false), (0, true));
assert_eq!(usize::MAX.carrying_add(1, true), (1, true));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Calculates `self - rhs - borrow`

without the ability to overflow.

Performs “ternary subtraction” which takes in an extra bit to subtract, and may return an additional bit of overflow. This allows for chaining together multiple subtractions to create “big integers” which represent larger values.

##### Examples

Basic usage

```
#![feature(bigint_helper_methods)]
assert_eq!(5usize.borrowing_sub(2, false), (3, false));
assert_eq!(5usize.borrowing_sub(2, true), (2, false));
assert_eq!(0usize.borrowing_sub(1, false), (usize::MAX, true));
assert_eq!(0usize.borrowing_sub(1, true), (usize::MAX - 1, true));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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 0.

##### Examples

Basic usage

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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 0.

##### Examples

Basic usage

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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 0.

##### Examples

Basic usage

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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 0.

##### Examples

Basic usage

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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));
```

Run## This is supported on **64-bit** only.

**64-bit**only.

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

Basic usage

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

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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 0.

##### Examples

Basic usage:

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

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

Calculates the smallest value greater than or equal to `self`

that
is a multiple of `rhs`

.

##### Panics

This function will panic if `rhs`

is 0 or the operation results in overflow.

##### Examples

Basic usage:

```
#![feature(int_roundings)]
assert_eq!(16_usize.unstable_next_multiple_of(8), 16);
assert_eq!(23_usize.unstable_next_multiple_of(8), 24);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Calculates the smallest value greater than or equal to `self`

that
is a multiple of `rhs`

. Returns `None`

is `rhs`

is zero or the
operation would result in overflow.

##### Examples

Basic usage:

```
#![feature(int_roundings)]
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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

## This is supported on **64-bit** only.

**64-bit**only.

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 method can return 0).

##### Examples

Basic usage:

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

Run## This is supported on **64-bit** only.

**64-bit**only.

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:

```
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);
```

Run## 🔬 This is a nightly-only experimental API. (`wrapping_next_power_of_two`

#32463)

needs decision on wrapping behaviour

This is supported on **64-bit** only.

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

#32463)

needs decision on wrapping behaviour

**64-bit**only.

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);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Return 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]);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Return 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]);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Return 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]
}
);
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Create 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);
```

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

```
use std::convert::TryInto;
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())
}
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Create 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);
```

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

```
use std::convert::TryInto;
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())
}
```

Run## This is supported on **64-bit** only.

**64-bit**only.

Create 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);
```

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

```
use std::convert::TryInto;
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())
}
```

Run## 👎 Deprecating in a future Rust version: replaced by the `MIN`

associated constant on this type

This is supported on **64-bit** only.

replaced by the `MIN`

associated constant on this type

**64-bit**only.

New code should prefer to use
`usize::MIN`

instead.

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

## 👎 Deprecating in a future Rust version: replaced by the `MAX`

associated constant on this type

This is supported on **64-bit** only.

replaced by the `MAX`

associated constant on this type

**64-bit**only.

New code should prefer to use
`usize::MAX`

instead.

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

## Trait Implementations

Performs the `+=`

operation. Read more

Performs the `+=`

operation. Read more

Performs the `&=`

operation. Read more

Performs the `&=`

operation. Read more

#### type Output = NonZeroUsize

#### type Output = NonZeroUsize

The resulting type after applying the `|`

operator.

Performs the `|`

operation. Read more

Performs the `|=`

operation. Read more

Performs the `|=`

operation. Read more

Performs the `^=`

operation. Read more

Performs the `^=`

operation. Read more

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

## Panics

This operation will panic if `other == 0`

.

Performs the `/=`

operation. Read more

Performs the `/=`

operation. Read more

Converts a `NonZeroUsize`

into an `usize`

#### type Err = ParseIntError

#### type Err = ParseIntError

The associated error which can be returned from parsing.

Performs the `*=`

operation. Read more

Performs the `*=`

operation. Read more

This method returns an ordering between `self`

and `other`

values if one exists. Read more

This method tests less than (for `self`

and `other`

) and is used by the `<`

operator. Read more

This method tests less than or equal to (for `self`

and `other`

) and is used by the `<=`

operator. Read more

This method tests greater than or equal to (for `self`

and `other`

) and is used by the `>=`

operator. Read more

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`

.

Performs the `%=`

operation. Read more

Performs the `%=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `<<=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

Performs the `>>=`

operation. Read more

#### type Output = T

#### type Output = T

The output type returned by methods.

`slice_index_methods`

)Returns a shared reference to the output at this location, if in bounds. Read more

`slice_index_methods`

)Returns a mutable reference to the output at this location, if in bounds. Read more

`slice_index_methods`

)Returns a shared reference to the output at this location, without
performing any bounds checking.
Calling this method with an out-of-bounds index or a dangling `slice`

pointer
is *undefined behavior* even if the resulting reference is not used. Read more

`slice_index_methods`

)Returns a mutable reference to the output at this location, without
performing any bounds checking.
Calling this method with an out-of-bounds index or a dangling `slice`

pointer
is *undefined behavior* even if the resulting reference is not used. Read more

`slice_index_methods`

)Returns a shared reference to the output at this location, panicking if out of bounds. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *successor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *predecessor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *successor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the value that would be obtained by taking the *predecessor*
of `self`

`count`

times. Read more

## 🔬 This is a nightly-only experimental API. (`step_trait`

#42168)

recently redesigned

Returns the number of *successor* steps required to get from `start`

to `end`

. Read more

Performs the `-=`

operation. Read more

Performs the `-=`

operation. Read more

Try to create the target number type from a source number type. This returns an error if the source value is outside of the range of the target type.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

Try to create the target number type from a source number type. This returns an error if the source value is outside of the range of the target type.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

Try to create the target number type from a source number type. This returns an error if the source value is outside of the range of the target type.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

#### type Error = TryFromIntError

#### type Error = TryFromIntError

The type returned in the event of a conversion error.

## Auto Trait Implementations

### impl RefUnwindSafe for usize

### impl UnwindSafe for usize

## Blanket Implementations

Mutably borrows from an owned value. Read more