# 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.

source

#### 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