# Type Alias core::num::NonZeroI32

1.34.0 · source ·

    pub type NonZeroI32 = NonZero<i32>;

Expand description

An integer that is known not to equal zero.

This enables some memory layout optimization. For example, `Option<NonZeroI32>` is the same size as `i32`:

    use std::mem::size_of;
    assert_eq!(size_of::<Option<core::num::NonZeroI32>>(), size_of::<i32>());

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## §Layout

`NonZeroI32` is guaranteed to have the same layout and bit validity as `i32` with the exception that `0` is not a valid instance. `Option<NonZeroI32>` is guaranteed to be compatible with `i32`, including in FFI.

Thanks to the null pointer optimization, `NonZeroI32` and `Option<NonZeroI32>` are guaranteed to have the same size and alignment:

    use std::num::NonZeroI32;

    assert_eq!(size_of::<NonZeroI32>(), size_of::<Option<NonZeroI32>>());
    assert_eq!(align_of::<NonZeroI32>(), align_of::<Option<NonZeroI32>>());

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## Aliased Type§

    struct NonZeroI32(/* private fields */);

## Implementations§

source§

### impl NonZeroI32

1.67.0 · source

#### pub const BITS: u32 = 32u32

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

This value is equal to `i32::BITS`.

##### §Examples

    assert_eq!(NonZeroI32::BITS, i32::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::NonZeroI32::new(-1i32).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::NonZeroI32::new(0b0101000).unwrap();

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

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const: unstable · source

#### pub fn count_ones(self) -> NonZero<u32>

🔬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(generic_nonzero, non_zero_count_ones)]
    let a = NonZero::<i32>::new(0b100_0000)?;
    let b = NonZero::<i32>::new(0b100_0011)?;

    assert_eq!(a.count_ones(), NonZero::new(1)?);
    assert_eq!(b.count_ones(), NonZero::new(3)?);

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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, equal to `i32::MIN`.

Note: While most integer types are defined for every whole number between `MIN` and `MAX`, signed non-zero integers are a special case. They have a “gap” at 0.

##### §Examples

    assert_eq!(NonZeroI32::MIN.get(), i32::MIN);

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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 `i32::MAX`.

Note: While most integer types are defined for every whole number between `MIN` and `MAX`, signed non-zero integers are a special case. They have a “gap” at 0.

##### §Examples

    assert_eq!(NonZeroI32::MAX.get(), i32::MAX);

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1.64.0 (const: 1.64.0) · source

#### pub const fn abs(self) -> Self

Computes the absolute value of self. See `i32::abs` for documentation on overflow behaviour.

##### §Example

    let pos = NonZeroI32::new(1)?;
    let neg = NonZeroI32::new(-1)?;

    assert_eq!(pos, pos.abs());
    assert_eq!(pos, neg.abs());

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1.64.0 (const: 1.64.0) · source

#### pub const fn checked_abs(self) -> Option<Self>

Checked absolute value. Checks for overflow and returns `None` if `self == NonZeroI32::MIN`. The result cannot be zero.

##### §Example

    let pos = NonZeroI32::new(1)?;
    let neg = NonZeroI32::new(-1)?;
    let min = NonZeroI32::new(i32::MIN)?;

    assert_eq!(Some(pos), neg.checked_abs());
    assert_eq!(None, min.checked_abs());

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1.64.0 (const: 1.64.0) · source

#### pub const fn overflowing_abs(self) -> (Self, bool)

Computes the absolute value of self, with overflow information, see `i32::overflowing_abs`.

##### §Example

    let pos = NonZeroI32::new(1)?;
    let neg = NonZeroI32::new(-1)?;
    let min = NonZeroI32::new(i32::MIN)?;

    assert_eq!((pos, false), pos.overflowing_abs());
    assert_eq!((pos, false), neg.overflowing_abs());
    assert_eq!((min, true), min.overflowing_abs());

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1.64.0 (const: 1.64.0) · source

#### pub const fn saturating_abs(self) -> Self

Saturating absolute value, see `i32::saturating_abs`.

##### §Example

    let pos = NonZeroI32::new(1)?;
    let neg = NonZeroI32::new(-1)?;
    let min = NonZeroI32::new(i32::MIN)?;
    let min_plus = NonZeroI32::new(i32::MIN + 1)?;
    let max = NonZeroI32::new(i32::MAX)?;

    assert_eq!(pos, pos.saturating_abs());
    assert_eq!(pos, neg.saturating_abs());
    assert_eq!(max, min.saturating_abs());
    assert_eq!(max, min_plus.saturating_abs());

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1.64.0 (const: 1.64.0) · source

#### pub const fn wrapping_abs(self) -> Self

Wrapping absolute value, see `i32::wrapping_abs`.

##### §Example

    let pos = NonZeroI32::new(1)?;
    let neg = NonZeroI32::new(-1)?;
    let min = NonZeroI32::new(i32::MIN)?;

    assert_eq!(pos, pos.wrapping_abs());
    assert_eq!(pos, neg.wrapping_abs());
    assert_eq!(min, min.wrapping_abs());
    assert_eq!(max, (-max).wrapping_abs());

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1.64.0 (const: 1.64.0) · source

#### pub const fn unsigned_abs(self) -> NonZeroU32

Computes the absolute value of self without any wrapping or panicking.

##### §Example

    let u_pos = NonZeroU32::new(1)?;
    let i_pos = NonZeroI32::new(1)?;
    let i_neg = NonZeroI32::new(-1)?;
    let i_min = NonZeroI32::new(i32::MIN)?;
    let u_max = NonZeroU32::new(u32::MAX / 2 + 1)?;

    assert_eq!(u_pos, i_pos.unsigned_abs());
    assert_eq!(u_pos, i_neg.unsigned_abs());
    assert_eq!(u_max, i_min.unsigned_abs());

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1.71.0 (const: 1.71.0) · source

#### pub const fn is_positive(self) -> bool

Returns `true` if `self` is positive and `false` if the number is negative.

##### §Example

    let pos_five = NonZeroI32::new(5)?;
    let neg_five = NonZeroI32::new(-5)?;

    assert!(pos_five.is_positive());
    assert!(!neg_five.is_positive());

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1.71.0 (const: 1.71.0) · source

#### pub const fn is_negative(self) -> bool

Returns `true` if `self` is negative and `false` if the number is positive.

##### §Example

    let pos_five = NonZeroI32::new(5)?;
    let neg_five = NonZeroI32::new(-5)?;

    assert!(neg_five.is_negative());
    assert!(!pos_five.is_negative());

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1.71.0 (const: 1.71.0) · source

#### pub const fn checked_neg(self) -> Option<Self>

Checked negation. Computes `-self`, returning `None` if `self == NonZeroI32::MIN`.

##### §Example

    let pos_five = NonZeroI32::new(5)?;
    let neg_five = NonZeroI32::new(-5)?;
    let min = NonZeroI32::new(i32::MIN)?;

    assert_eq!(pos_five.checked_neg(), Some(neg_five));
    assert_eq!(min.checked_neg(), None);

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1.71.0 (const: 1.71.0) · source

#### pub const fn overflowing_neg(self) -> (Self, bool)

Negates self, overflowing if this is equal to the minimum value.

See `i32::overflowing_neg` for documentation on overflow behaviour.

##### §Example

    let pos_five = NonZeroI32::new(5)?;
    let neg_five = NonZeroI32::new(-5)?;
    let min = NonZeroI32::new(i32::MIN)?;

    assert_eq!(pos_five.overflowing_neg(), (neg_five, false));
    assert_eq!(min.overflowing_neg(), (min, true));

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1.71.0 (const: 1.71.0) · source

#### pub const fn saturating_neg(self) -> Self

Saturating negation. Computes `-self`, returning `NonZeroI32::MAX` if `self == NonZeroI32::MIN` instead of overflowing.

##### §Example

    let pos_five = NonZeroI32::new(5)?;
    let neg_five = NonZeroI32::new(-5)?;
    let min = NonZeroI32::new(i32::MIN)?;
    let min_plus_one = NonZeroI32::new(i32::MIN + 1)?;
    let max = NonZeroI32::new(i32::MAX)?;

    assert_eq!(pos_five.saturating_neg(), neg_five);
    assert_eq!(min.saturating_neg(), max);
    assert_eq!(max.saturating_neg(), min_plus_one);

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1.71.0 (const: 1.71.0) · source

#### pub const fn wrapping_neg(self) -> Self

Wrapping (modular) negation. Computes `-self`, wrapping around at the boundary of the type.

See `i32::wrapping_neg` for documentation on overflow behaviour.

##### §Example

    let pos_five = NonZeroI32::new(5)?;
    let neg_five = NonZeroI32::new(-5)?;
    let min = NonZeroI32::new(i32::MIN)?;

    assert_eq!(pos_five.wrapping_neg(), neg_five);
    assert_eq!(min.wrapping_neg(), min);

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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 = NonZeroI32::new(2)?;
    let four = NonZeroI32::new(4)?;
    let max = NonZeroI32::new(i32::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 `NonZeroI32::MAX` on overflow.

##### §Examples

    let two = NonZeroI32::new(2)?;
    let four = NonZeroI32::new(4)?;
    let max = NonZeroI32::new(i32::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 > i32::MAX`, or `self * rhs < i32::MIN`.

##### §Examples

    #![feature(nonzero_ops)]

    let two = NonZeroI32::new(2)?;
    let four = NonZeroI32::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 = NonZeroI32::new(3)?;
    let twenty_seven = NonZeroI32::new(27)?;
    let half_max = NonZeroI32::new(i32::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 `NonZeroI32::MIN` or `NonZeroI32::MAX` on overflow.

##### §Examples

    let three = NonZeroI32::new(3)?;
    let twenty_seven = NonZeroI32::new(27)?;
    let max = NonZeroI32::new(i32::MAX)?;

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

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## Trait Implementations§

1.35.0 · source§

### impl FromStr for NonZeroI32

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#### type Err = ParseIntError

The associated error which can be returned from parsing.
source§

#### fn from_str(src: &str) -> Result<Self, Self::Err>

Parses a string `s` to return a value of this type. Read more
1.71.0 · source§

### impl Neg for &NonZeroI32

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#### type Output = <NonZero<i32> as Neg>::Output

The resulting type after applying the `-` operator.
source§

#### fn neg(self) -> <NonZeroI32 as Neg>::Output

Performs the unary `-` operation. Read more
1.71.0 · source§

### impl Neg for NonZeroI32

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#### type Output = NonZero<i32>

The resulting type after applying the `-` operator.
source§

#### fn neg(self) -> Self

Performs the unary `-` operation. Read more