Type Alias core::num::NonZeroU32

1.28.0 · source ·
pub type NonZeroU32 = NonZero<u32>;
Expand description

An integer that is known not to equal zero.

This enables some memory layout optimization. For example, Option<NonZeroU32> is the same size as u32:

use std::mem::size_of;
assert_eq!(size_of::<Option<core::num::NonZeroU32>>(), size_of::<u32>());
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§Layout

NonZeroU32 is guaranteed to have the same layout and bit validity as u32 with the exception that 0 is not a valid instance. Option<NonZeroU32> is guaranteed to be compatible with u32, including in FFI.

Thanks to the null pointer optimization, NonZeroU32 and Option<NonZeroU32> are guaranteed to have the same size and alignment:

use std::num::NonZeroU32;

assert_eq!(size_of::<NonZeroU32>(), size_of::<Option<NonZeroU32>>());
assert_eq!(align_of::<NonZeroU32>(), align_of::<Option<NonZeroU32>>());
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Aliased Type§

struct NonZeroU32(/* private fields */);

Implementations§

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impl NonZeroU32

const: 1.28.0 · source

pub const unsafe fn new_unchecked(n: u32) -> 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(n: u32) -> Option<Self>

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

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pub unsafe fn from_mut_unchecked(n: &mut u32) -> &mut Self

🔬This is a nightly-only experimental API. (nonzero_from_mut #106290)

Converts a primitive mutable reference to a non-zero mutable reference without checking whether the referenced value is non-zero. This results in undefined behavior if *n is zero.

§Safety

The referenced value must not be currently zero.

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pub fn from_mut(n: &mut u32) -> Option<&mut Self>

🔬This is a nightly-only experimental API. (nonzero_from_mut #106290)

Converts a primitive mutable reference to a non-zero mutable reference if the referenced integer is not zero.

const: 1.34.0 · source

pub const fn get(self) -> u32

Returns the value as a primitive type.

1.67.0 · source

pub const BITS: u32 = 32u32

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

This value is equal to u32::BITS.

§Examples

assert_eq!(NonZeroU32::BITS, u32::BITS);
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1.53.0 (const: 1.53.0) · source

pub const fn leading_zeros(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::NonZeroU32::new(u32::MAX).unwrap();

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

pub const fn trailing_zeros(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::NonZeroU32::new(0b0101000).unwrap();

assert_eq!(n.trailing_zeros(), 3);
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const: unstable · source

pub fn count_ones(self) -> NonZeroU32

🔬This is a nightly-only experimental API. (non_zero_count_ones #120287)

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

§Examples

Basic usage:

#![feature(non_zero_count_ones)]

let one = num::NonZeroU32::new(1)?;
let three = num::NonZeroU32::new(3)?;
let a = NonZeroU32::new(0b100_0000)?;
let b = NonZeroU32::new(0b100_0011)?;

assert_eq!(a.count_ones(), one);
assert_eq!(b.count_ones(), three);
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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!(NonZeroU32::MIN.get(), 1u32);
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1.70.0 · source

pub const MAX: Self = _

The largest value that can be represented by this non-zero integer type, equal to u32::MAX.

§Examples
assert_eq!(NonZeroU32::MAX.get(), u32::MAX);
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1.64.0 (const: 1.64.0) · source

pub const fn checked_add(self, other: u32) -> Option<Self>

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 = NonZeroU32::new(1)?;
let two = NonZeroU32::new(2)?;
let max = NonZeroU32::new(u32::MAX)?;

assert_eq!(Some(two), one.checked_add(1));
assert_eq!(None, max.checked_add(1));
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1.64.0 (const: 1.64.0) · source

pub const fn saturating_add(self, other: u32) -> Self

Adds an unsigned integer to a non-zero value. Return NonZeroU32::MAX on overflow.

§Examples
let one = NonZeroU32::new(1)?;
let two = NonZeroU32::new(2)?;
let max = NonZeroU32::new(u32::MAX)?;

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

pub const unsafe fn unchecked_add(self, other: u32) -> Self

🔬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 > u32::MAX.

§Examples
#![feature(nonzero_ops)]

let one = NonZeroU32::new(1)?;
let two = NonZeroU32::new(2)?;

assert_eq!(two, unsafe { one.unchecked_add(1) });
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1.64.0 (const: 1.64.0) · source

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

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 = NonZeroU32::new(2)?;
let three = NonZeroU32::new(3)?;
let four = NonZeroU32::new(4)?;
let max = NonZeroU32::new(u32::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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1.67.0 (const: 1.67.0) · source

pub const fn ilog2(self) -> u32

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

This is the same operation as u32::ilog2, except that it has no failure cases to worry about since this value can never be zero.

§Examples
assert_eq!(NonZeroU32::new(7).unwrap().ilog2(), 2);
assert_eq!(NonZeroU32::new(8).unwrap().ilog2(), 3);
assert_eq!(NonZeroU32::new(9).unwrap().ilog2(), 3);
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1.67.0 (const: 1.67.0) · source

pub const fn ilog10(self) -> u32

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

This is the same operation as u32::ilog10, except that it has no failure cases to worry about since this value can never be zero.

§Examples
assert_eq!(NonZeroU32::new(99).unwrap().ilog10(), 1);
assert_eq!(NonZeroU32::new(100).unwrap().ilog10(), 2);
assert_eq!(NonZeroU32::new(101).unwrap().ilog10(), 2);
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const: unstable · source

pub fn midpoint(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 = NonZeroU32::new(1)?;
let two = NonZeroU32::new(2)?;
let four = NonZeroU32::new(4)?;

assert_eq!(one.midpoint(four), two);
assert_eq!(four.midpoint(one), two);
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1.59.0 (const: 1.59.0) · source

pub const fn is_power_of_two(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::NonZeroU32::new(8).unwrap();
assert!(eight.is_power_of_two());
let ten = std::num::NonZeroU32::new(10).unwrap();
assert!(!ten.is_power_of_two());
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1.64.0 (const: 1.64.0) · source

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

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 = NonZeroU32::new(2)?;
let four = NonZeroU32::new(4)?;
let max = NonZeroU32::new(u32::MAX)?;

assert_eq!(Some(four), two.checked_mul(two));
assert_eq!(None, max.checked_mul(two));
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1.64.0 (const: 1.64.0) · source

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

Multiplies two non-zero integers together. Return NonZeroU32::MAX on overflow.

§Examples
let two = NonZeroU32::new(2)?;
let four = NonZeroU32::new(4)?;
let max = NonZeroU32::new(u32::MAX)?;

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

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

🔬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 > u32::MAX.

§Examples
#![feature(nonzero_ops)]

let two = NonZeroU32::new(2)?;
let four = NonZeroU32::new(4)?;

assert_eq!(four, unsafe { two.unchecked_mul(two) });
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1.64.0 (const: 1.64.0) · source

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

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 = NonZeroU32::new(3)?;
let twenty_seven = NonZeroU32::new(27)?;
let half_max = NonZeroU32::new(u32::MAX / 2)?;

assert_eq!(Some(twenty_seven), three.checked_pow(3));
assert_eq!(None, half_max.checked_pow(3));
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1.64.0 (const: 1.64.0) · source

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

Raise non-zero value to an integer power. Return NonZeroU32::MAX on overflow.

§Examples
let three = NonZeroU32::new(3)?;
let twenty_seven = NonZeroU32::new(27)?;
let max = NonZeroU32::new(u32::MAX)?;

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

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impl Binary for NonZeroU32

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

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

impl BitOr<u32> for NonZeroU32

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type Output = NonZero<u32>

The resulting type after applying the | operator.
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fn bitor(self, rhs: u32) -> Self::Output

Performs the | operation. Read more
1.45.0 · source§

impl BitOr for NonZeroU32

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type Output = NonZero<u32>

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 BitOrAssign<u32> for NonZeroU32

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fn bitor_assign(&mut self, rhs: u32)

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

impl BitOrAssign for NonZeroU32

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fn bitor_assign(&mut self, rhs: Self)

Performs the |= operation. Read more
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impl Clone for NonZeroU32

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fn clone(&self) -> Self

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 NonZeroU32

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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 NonZeroU32

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

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

impl From<NonZero<u16>> for NonZeroU32

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fn from(small: NonZeroU16) -> Self

Converts NonZeroU16 to NonZeroU32 losslessly.

1.41.0 · source§

impl From<NonZero<u8>> for NonZeroU32

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fn from(small: NonZeroU8) -> Self

Converts NonZeroU8 to NonZeroU32 losslessly.

1.35.0 · source§

impl FromStr for NonZeroU32

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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 NonZeroU32

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

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 NonZeroU32

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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 NonZeroU32

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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 NonZeroU32

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

This method returns an Ordering between self and other. Read more
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fn max(self, other: Self) -> Self

Compares and returns the maximum of two values. Read more
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fn min(self, other: Self) -> Self

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval. Read more
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impl PartialEq for NonZeroU32

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

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Self) -> 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 for NonZeroU32

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

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Self) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Self) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Self) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Self) -> bool

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

impl TryFrom<NonZero<i128>> for NonZeroU32

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

Attempts to convert NonZeroI128 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<NonZero<i16>> for NonZeroU32

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

Attempts to convert NonZeroI16 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<NonZero<i32>> for NonZeroU32

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

Attempts to convert NonZeroI32 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<NonZero<i64>> for NonZeroU32

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

Attempts to convert NonZeroI64 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<NonZero<i8>> for NonZeroU32

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

Attempts to convert NonZeroI8 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<NonZero<isize>> for NonZeroU32

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

Attempts to convert NonZeroIsize 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<NonZero<u128>> for NonZeroU32

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

Attempts to convert NonZeroU128 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<NonZero<u64>> for NonZeroU32

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

Attempts to convert NonZeroU64 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<NonZero<usize>> 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.
1.46.0 · source§

impl TryFrom<u32> for NonZeroU32

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fn try_from(value: u32) -> Result<Self, Self::Error>

Attempts to convert u32 to NonZeroU32.

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type Error = TryFromIntError

The type returned in the event of a conversion error.
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impl UpperHex for NonZeroU32

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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 NonZeroU32

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impl Eq for NonZeroU32

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impl StructuralPartialEq for NonZeroU32