## NonZeroU16

# Type Alias NonZeroU16

1.28.0 · Source

    pub type NonZeroU16 = NonZero<u16>;

Expand description

A `u16` that is known not to equal zero.

This enables some memory layout optimization. For example, `Option<NonZeroU16>` is the same size as `u16`:

    assert_eq!(size_of::<Option<core::num::NonZeroU16>>(), size_of::<u16>());

## §Layout

`NonZeroU16` is guaranteed to have the same layout and bit validity as `u16` with the exception that `0` is not a valid instance. `Option<NonZeroU16>` is guaranteed to be compatible with `u16`, including in FFI.

Thanks to the null pointer optimization, `NonZeroU16` and `Option<NonZeroU16>` are guaranteed to have the same size and alignment:

    use std::num::NonZeroU16;

    assert_eq!(size_of::<NonZeroU16>(), size_of::<Option<NonZeroU16>>());
    assert_eq!(align_of::<NonZeroU16>(), align_of::<Option<NonZeroU16>>());

## §Compile-time creation

Since both `Option::unwrap()` and `Option::expect()` are `const`, it is possible to define a new `NonZeroU16` at compile time via:

    use std::num::NonZeroU16;

    const TEN: NonZeroU16 = NonZeroU16::new(10).expect("ten is non-zero");

## Aliased Type§

    pub struct NonZeroU16(/* private fields */);