Struct core::num::NonZeroUsize

1.28.0 · source ·
#[repr(transparent)]
pub struct NonZeroUsize(/* private fields */);
Expand description

An integer that is known not to equal zero.

This enables some memory layout optimization. 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

Layout

NonZeroUsize is guaranteed to have the same layout and bit validity as usize with the exception that 0 is not a valid instance. Option<NonZeroUsize> is guaranteed to be compatible with usize, including in FFI.

Thanks to the null pointer optimization, NonZeroUsize and Option<NonZeroUsize> are guaranteed to have the same size and alignment:

use std::num::NonZeroUsize;

assert_eq!(size_of::<NonZeroUsize>(), size_of::<Option<NonZeroUsize>>());
assert_eq!(align_of::<NonZeroUsize>(), align_of::<Option<NonZeroUsize>>());
Run

Implementations§

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impl NonZeroUsize

const: 1.28.0 · source

pub const unsafe fn new_unchecked<const host: bool = true>(n: usize) -> Self

Creates a non-zero without checking whether the value is non-zero. This results in undefined behaviour if the value is zero.

Safety

The value must not be zero.

const: 1.47.0 · source

pub const fn new<const host: bool = true>(n: usize) -> Option<Self>

Creates a non-zero if the given value is not zero.

const: 1.34.0 · source

pub const fn get<const host: bool = true>(self) -> usize

Returns the value as a primitive type.

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impl NonZeroUsize

1.53.0 (const: 1.53.0) · source

pub const fn leading_zeros<const host: bool = true>(self) -> u32

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

On many architectures, this function can perform better than leading_zeros() on the underlying integer type, as special handling of zero can be avoided.

Examples

Basic usage:

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

assert_eq!(n.leading_zeros(), 0);
Run
1.53.0 (const: 1.53.0) · source

pub const fn trailing_zeros<const host: bool = true>(self) -> u32

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

On many architectures, this function can perform better than trailing_zeros() on the underlying integer type, as special handling of zero can be avoided.

Examples

Basic usage:

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

assert_eq!(n.trailing_zeros(), 3);
Run
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impl NonZeroUsize

1.64.0 (const: 1.64.0) · source

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

Adds an unsigned integer to a non-zero value. Checks for overflow and returns None on overflow. As a consequence, the result cannot wrap to zero.

Examples
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));
Run
1.64.0 (const: 1.64.0) · source

pub const fn saturating_add<const host: bool = true>( self, other: usize ) -> NonZeroUsize

Adds an unsigned integer to a non-zero value. Return NonZeroUsize::MAX on overflow.

Examples
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));
Run
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pub const unsafe fn unchecked_add<const host: bool = true>( self, other: usize ) -> NonZeroUsize

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

Adds an unsigned integer to a non-zero value, assuming overflow cannot occur. Overflow is unchecked, and it is undefined behaviour to overflow even if the result would wrap to a non-zero value. The behaviour is undefined as soon as 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) });
Run
1.64.0 (const: 1.64.0) · source

pub const fn checked_next_power_of_two<const host: bool = true>( self ) -> Option<NonZeroUsize>

Returns the smallest power of two greater than or equal to n. Checks for overflow and returns None if the next power of two is greater than the type’s maximum value. As a consequence, the result cannot wrap to zero.

Examples
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() );
Run
1.67.0 (const: 1.67.0) · source

pub const fn ilog2<const host: bool = true>(self) -> u32

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

This is the same operation as usize::ilog2, except that it has no failure cases to worry about since this value can never be zero.

Examples
assert_eq!(NonZeroUsize::new(7).unwrap().ilog2(), 2);
assert_eq!(NonZeroUsize::new(8).unwrap().ilog2(), 3);
assert_eq!(NonZeroUsize::new(9).unwrap().ilog2(), 3);
Run
1.67.0 (const: 1.67.0) · source

pub const fn ilog10<const host: bool = true>(self) -> u32

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

This is the same operation as usize::ilog10, except that it has no failure cases to worry about since this value can never be zero.

Examples
assert_eq!(NonZeroUsize::new(99).unwrap().ilog10(), 1);
assert_eq!(NonZeroUsize::new(100).unwrap().ilog10(), 2);
assert_eq!(NonZeroUsize::new(101).unwrap().ilog10(), 2);
Run
const: unstable · source

pub fn midpoint<const host: bool = true>(self, rhs: Self) -> Self

🔬This is a nightly-only experimental API. (num_midpoint #110840)

Calculates the middle point of self and rhs.

midpoint(a, b) is (a + b) >> 1 as if it were performed in a sufficiently-large signed integral type. This implies that the result is always rounded towards negative infinity and that no overflow will ever occur.

Examples
#![feature(num_midpoint)]

let one = NonZeroUsize::new(1)?;
let two = NonZeroUsize::new(2)?;
let four = NonZeroUsize::new(4)?;

assert_eq!(one.midpoint(four), two);
assert_eq!(four.midpoint(one), two);
Run
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impl NonZeroUsize

1.64.0 (const: 1.64.0) · source

pub const fn checked_mul<const host: bool = true>( self, other: NonZeroUsize ) -> Option<NonZeroUsize>

Multiplies two non-zero integers together. Checks for overflow and returns None on overflow. As a consequence, the result cannot wrap to zero.

Examples
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
1.64.0 (const: 1.64.0) · source

pub const fn saturating_mul<const host: bool = true>( self, other: NonZeroUsize ) -> NonZeroUsize

Multiplies two non-zero integers together. Return NonZeroUsize::MAX on overflow.

Examples
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
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pub const unsafe fn unchecked_mul<const host: bool = true>( self, other: NonZeroUsize ) -> NonZeroUsize

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

Multiplies two non-zero integers together, assuming overflow cannot occur. Overflow is unchecked, and it is undefined behaviour to overflow even if the result would wrap to a non-zero value. The behaviour is undefined as soon as 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
1.64.0 (const: 1.64.0) · source

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

Raises non-zero value to an integer power. Checks for overflow and returns None on overflow. As a consequence, the result cannot wrap to zero.

Examples
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));
Run
1.64.0 (const: 1.64.0) · source

pub const fn saturating_pow<const host: bool = true>( self, other: u32 ) -> NonZeroUsize

Raise non-zero value to an integer power. Return NonZeroUsize::MAX on overflow.

Examples
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
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impl NonZeroUsize

1.59.0 (const: 1.59.0) · source

pub const fn is_power_of_two<const host: bool = true>(self) -> bool

Returns true if and only if self == (1 << k) for some k.

On many architectures, this function can perform better than is_power_of_two() on the underlying integer type, as special handling of zero can be avoided.

Examples

Basic usage:

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());
Run
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impl NonZeroUsize

1.70.0 · source

pub const MIN: Self = _

The smallest value that can be represented by this non-zero integer type, 1.

Examples
assert_eq!(NonZeroUsize::MIN.get(), 1usize);
Run
1.70.0 · source

pub const MAX: Self = _

The largest value that can be represented by this non-zero integer type, equal to usize::MAX.

Examples
assert_eq!(NonZeroUsize::MAX.get(), usize::MAX);
Run
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impl NonZeroUsize

1.67.0 · source

pub const BITS: u32 = 64u32

The size of this non-zero integer type in bits.

This value is equal to usize::BITS.

Examples

assert_eq!(NonZeroUsize::BITS, usize::BITS);
Run

Trait Implementations§

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impl Binary for NonZeroUsize

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.
1.45.0 · source§

impl BitOr<NonZeroUsize> for NonZeroUsize

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type Output = NonZeroUsize

The resulting type after applying the | operator.
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fn bitor(self, rhs: Self) -> Self::Output

Performs the | operation. Read more
1.45.0 · source§

impl BitOr<NonZeroUsize> for usize

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type Output = NonZeroUsize

The resulting type after applying the | operator.
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fn bitor(self, rhs: NonZeroUsize) -> Self::Output

Performs the | operation. Read more
1.45.0 · source§

impl BitOr<usize> for NonZeroUsize

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type Output = NonZeroUsize

The resulting type after applying the | operator.
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fn bitor(self, rhs: usize) -> Self::Output

Performs the | operation. Read more
1.45.0 · source§

impl BitOrAssign<NonZeroUsize> for NonZeroUsize

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fn bitor_assign(&mut self, rhs: Self)

Performs the |= operation. Read more
1.45.0 · source§

impl BitOrAssign<usize> for NonZeroUsize

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fn bitor_assign(&mut self, rhs: usize)

Performs the |= operation. Read more
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impl Clone for NonZeroUsize

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fn clone(&self) -> NonZeroUsize

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from source. Read more
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impl Debug for NonZeroUsize

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl Display for NonZeroUsize

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
1.51.0 · source§

impl Div<NonZeroUsize> for usize

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

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

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type Output = usize

The resulting type after applying the / operator.
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impl From<Alignment> for NonZeroUsize

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fn from(align: Alignment) -> NonZeroUsize

Converts to this type from the input type.
1.41.0 · source§

impl From<NonZeroU16> for NonZeroUsize

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fn from(small: NonZeroU16) -> Self

Converts NonZeroU16 to NonZeroUsize losslessly.

1.41.0 · source§

impl From<NonZeroU8> for NonZeroUsize

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fn from(small: NonZeroU8) -> Self

Converts NonZeroU8 to NonZeroUsize losslessly.

1.31.0 · source§

impl From<NonZeroUsize> for usize

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fn from(nonzero: NonZeroUsize) -> Self

Converts a NonZeroUsize into an usize

1.35.0 · source§

impl FromStr for NonZeroUsize

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type Err = ParseIntError

The associated error which can be returned from parsing.
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fn from_str(src: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type. Read more
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impl Hash for NonZeroUsize

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fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher. Read more
1.3.0 · source§

fn hash_slice<H: Hasher>(data: &[Self], state: &mut H)where Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl LowerHex for NonZeroUsize

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.
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impl Octal for NonZeroUsize

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.
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impl Ord for NonZeroUsize

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fn cmp(&self, other: &NonZeroUsize) -> Ordering

This method returns an Ordering between self and other. Read more
1.21.0 · source§

fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more
1.21.0 · source§

fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more
1.50.0 · source§

fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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impl PartialEq<NonZeroUsize> for NonZeroUsize

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

This method tests for self and other values to be equal, and is used by ==.
1.0.0 · source§

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialOrd<NonZeroUsize> for NonZeroUsize

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fn partial_cmp(&self, other: &NonZeroUsize) -> Option<Ordering>

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

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

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

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

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

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

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

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

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
1.51.0 · source§

impl Rem<NonZeroUsize> for usize

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

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

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type Output = usize

The resulting type after applying the % operator.
1.49.0 · source§

impl TryFrom<NonZeroI128> for NonZeroUsize

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fn try_from(value: NonZeroI128) -> Result<Self, Self::Error>

Attempts to convert NonZeroI128 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroI16> for NonZeroUsize

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fn try_from(value: NonZeroI16) -> Result<Self, Self::Error>

Attempts to convert NonZeroI16 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroI32> for NonZeroUsize

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fn try_from(value: NonZeroI32) -> Result<Self, Self::Error>

Attempts to convert NonZeroI32 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroI64> for NonZeroUsize

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fn try_from(value: NonZeroI64) -> Result<Self, Self::Error>

Attempts to convert NonZeroI64 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroI8> for NonZeroUsize

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fn try_from(value: NonZeroI8) -> Result<Self, Self::Error>

Attempts to convert NonZeroI8 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroIsize> for NonZeroUsize

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fn try_from(value: NonZeroIsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroIsize to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroU128> for NonZeroUsize

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fn try_from(value: NonZeroU128) -> Result<Self, Self::Error>

Attempts to convert NonZeroU128 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroU32> for NonZeroUsize

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fn try_from(value: NonZeroU32) -> Result<Self, Self::Error>

Attempts to convert NonZeroU32 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroU64> for NonZeroUsize

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fn try_from(value: NonZeroU64) -> Result<Self, Self::Error>

Attempts to convert NonZeroU64 to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
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impl TryFrom<NonZeroUsize> for Alignment

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type Error = TryFromIntError

The type returned in the event of a conversion error.
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fn try_from(align: NonZeroUsize) -> Result<Alignment, Self::Error>

Performs the conversion.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroI128

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroI128.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroI16

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroI16.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroI32

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroI32.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroI64

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroI64.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroI8

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroI8.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroIsize

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroIsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroU128

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroU128.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroU16

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroU16.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroU32

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroU32.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroU64

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroU64.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.49.0 · source§

impl TryFrom<NonZeroUsize> for NonZeroU8

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fn try_from(value: NonZeroUsize) -> Result<Self, Self::Error>

Attempts to convert NonZeroUsize to NonZeroU8.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
1.46.0 · source§

impl TryFrom<usize> for NonZeroUsize

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fn try_from(value: usize) -> Result<Self, Self::Error>

Attempts to convert usize to NonZeroUsize.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
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impl UpperHex for NonZeroUsize

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.
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impl Copy for NonZeroUsize

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impl Eq for NonZeroUsize

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impl StructuralEq for NonZeroUsize

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impl StructuralPartialEq for NonZeroUsize

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.