Struct core::num::NonZeroUsize1.28.0[−][src]

#[repr(transparent)]
pub struct NonZeroUsize(_);

Expand description

已知不等于零的整数。

这样可以进行一些内存布局优化。 For example, Option<NonZeroUsize> is the same size as usize:

use std::mem::size_of;
assert_eq!(size_of::<Option<core::num::NonZeroUsize>>(), size_of::<usize>());

Run

Implementations

impl NonZeroUsize

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pub const unsafe fn new_unchecked(n: usize) -> Self

1.28.0 (const: 1.28.0)[src]

创建一个非零值而不检查该值是否为非零值。如果该值为零，这将导致未定义的行为。

Safety

该值不能为零。

pub const fn new(n: usize) -> Option<Self>

1.28.0 (const: 1.47.0)[src]

如果给定值不为零，则创建一个非零值。

pub const fn get(self) -> usize

1.28.0 (const: 1.34.0)[src]

以原始类型返回该值。

impl NonZeroUsize

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pub const fn leading_zeros(self) -> u32

1.53.0 (const: 1.53.0)[src]

返回 self 二进制表示形式中前导零的数目。

在许多体系结构上，此函数可以在基础整数类型上比 leading_zeros() 更好地执行，因为可以避免对零的特殊处理。

Examples

基本用法:

let n = std::num::NonZeroUsize::new(usize::MAX).unwrap();

assert_eq!(n.leading_zeros(), 0);

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pub const fn trailing_zeros(self) -> u32

1.53.0 (const: 1.53.0)[src]

返回 self 二进制表示形式中的尾随零数。

在许多体系结构上，此函数可以在基础整数类型上比 trailing_zeros() 更好地执行，因为可以避免对零的特殊处理。

Examples

基本用法:

let n = std::num::NonZeroUsize::new(0b0101000).unwrap();

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

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impl NonZeroUsize

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pub const fn checked_add(self, other: usize) -> Option<NonZeroUsize>

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

将无符号整数添加到非零值。检查溢出并在溢出时返回 None 因此，结果不能归零。

Examples

#![feature(nonzero_ops)]


let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
let max = NonZeroUsize::new(usize::MAX)?;

assert_eq!(Some(two), one.checked_add(1));
assert_eq!(None, max.checked_add(1));

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pub const fn saturating_add(self, other: usize) -> NonZeroUsize

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

将无符号整数添加到非零值。 Return usize::MAX on overflow.

Examples

#![feature(nonzero_ops)]

let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
let max = NonZeroUsize::new(usize::MAX)?;

assert_eq!(two, one.saturating_add(1));
assert_eq!(max, max.saturating_add(1));

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pub unsafe fn unchecked_add(self, other: usize) -> NonZeroUsize

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

假设不会发生溢出，将无符号整数添加到非零值。溢出未检查，如果结果将换行为非零值，则溢出 *even 是未定义的行为 *。

该行为是未定义的

self + rhs > usize::MAX.

Examples

#![feature(nonzero_ops)]

let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;

assert_eq!(two, unsafe { one.unchecked_add(1) });

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pub const fn checked_next_power_of_two(self) -> Option<NonZeroUsize>

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

返回大于或等于 n 的 2 的最小幂。如果下一个 2 的幂大于类型的最大值，则检查是否溢出并返回 None。因此，结果不能归零。

Examples

#![feature(nonzero_ops)]


let two = NonZeroUsize::new(2)?;
let three = NonZeroUsize::new(3)?;
let four = NonZeroUsize::new(4)?;
let max = NonZeroUsize::new(usize::MAX)?;

assert_eq!(Some(two), two.checked_next_power_of_two() );
assert_eq!(Some(four), three.checked_next_power_of_two() );
assert_eq!(None, max.checked_next_power_of_two() );

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impl NonZeroUsize

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pub const fn checked_mul(self, other: NonZeroUsize) -> Option<NonZeroUsize>

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

将两个非零整数相乘。检查溢出并在溢出时返回 None。因此，结果不能归零。

Examples

#![feature(nonzero_ops)]

let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;
let max = NonZeroUsize::new(usize::MAX)?;

assert_eq!(Some(four), two.checked_mul(two));
assert_eq!(None, max.checked_mul(two));

Run

pub const fn saturating_mul(self, other: NonZeroUsize) -> NonZeroUsize

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

将两个非零整数相乘。 Return usize::MAX on overflow.

Examples

#![feature(nonzero_ops)]

let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;
let max = NonZeroUsize::new(usize::MAX)?;

assert_eq!(four, two.saturating_mul(two));
assert_eq!(max, four.saturating_mul(max));

Run

pub unsafe fn unchecked_mul(self, other: NonZeroUsize) -> NonZeroUsize

[src]

🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

假设不会发生溢出，将两个非零整数相乘。溢出未检查，如果结果将换行为非零值，则溢出 *even 是未定义的行为 *。

该行为是未定义的

self * rhs > usize::MAX.

Examples

#![feature(nonzero_ops)]

let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;

assert_eq!(four, unsafe { two.unchecked_mul(two) });

Run

pub const fn checked_pow(self, other: u32) -> Option<NonZeroUsize>

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

将非零值提高到整数幂。检查溢出并在溢出时返回 None。因此，结果不能归零。

Examples

#![feature(nonzero_ops)]

let three = NonZeroUsize::new(3)?;
let twenty_seven = NonZeroUsize::new(27)?;
let half_max = NonZeroUsize::new(usize::MAX / 2)?;

assert_eq!(Some(twenty_seven), three.checked_pow(3));
assert_eq!(None, half_max.checked_pow(3));

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pub const fn saturating_pow(self, other: u32) -> NonZeroUsize

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🔬 This is a nightly-only experimental API. (nonzero_ops #84186)

将非零值提高到整数幂。 Return usize::MAX on overflow.

Examples

#![feature(nonzero_ops)]

let three = NonZeroUsize::new(3)?;
let twenty_seven = NonZeroUsize::new(27)?;
let max = NonZeroUsize::new(usize::MAX)?;

assert_eq!(twenty_seven, three.saturating_pow(3));
assert_eq!(max, max.saturating_pow(3));

Run

impl NonZeroUsize

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pub const fn is_power_of_two(self) -> bool

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🔬 This is a nightly-only experimental API. (nonzero_is_power_of_two #81106)

当且仅当某些 k 的 self == (1 << k) 时，才返回 true。

在许多体系结构上，此函数可以在基础整数类型上比 is_power_of_two() 更好地执行，因为可以避免对零的特殊处理。

Examples

基本用法:

#![feature(nonzero_is_power_of_two)]

let eight = std::num::NonZeroUsize::new(8).unwrap();
assert!(eight.is_power_of_two());
let ten = std::num::NonZeroUsize::new(10).unwrap();
assert!(!ten.is_power_of_two());