# Type Alias core::num::NonZeroI128

1.34.0 · source ·

    pub type NonZeroI128 = NonZero<i128>;

Expand description

An integer that is known not to equal zero.

This enables some memory layout optimization. For example, `Option<NonZeroI128>` is the same size as `i128`:

    use std::mem::size_of;
    assert_eq!(size_of::<Option<core::num::NonZeroI128>>(), size_of::<i128>());

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## §Layout

`NonZeroI128` is guaranteed to have the same layout and bit validity as `i128` with the exception that `0` is not a valid instance. `Option<NonZeroI128>` is guaranteed to be compatible with `i128`, including in FFI.

Thanks to the null pointer optimization, `NonZeroI128` and `Option<NonZeroI128>` are guaranteed to have the same size and alignment:

    use std::num::NonZeroI128;

    assert_eq!(size_of::<NonZeroI128>(), size_of::<Option<NonZeroI128>>());
    assert_eq!(align_of::<NonZeroI128>(), align_of::<Option<NonZeroI128>>());

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## Aliased Type§

    struct NonZeroI128(/* private fields */);