std::mem::variant_count - Rust
Description: API documentation for the Rust `variant_count` fn in crate `std`.
Keywords: rust, rustlang, rust-lang, variant_count

# [−][src]Function std::mem::variant_count

    pub fn variant_count<T>() -> usize

🔬 This is a nightly-only experimental API. (`variant_count` #73662)

Returns the number of variants in the enum type `T`.

If `T` is not an enum, calling this function will not result in undefined behavior, but the return value is unspecified. Equally, if `T` is an enum with more variants than `usize::MAX` the return value is unspecified. Uninhabited variants will be counted.

# Examples

    use std::mem;

    enum Void {}
    enum Foo { A(&'static str), B(i32), C(i32) }

    assert_eq!(mem::variant_count::<Void>(), 0);
    assert_eq!(mem::variant_count::<Foo>(), 3);

    assert_eq!(mem::variant_count::<Option<!>>(), 2);
    assert_eq!(mem::variant_count::<Result<!, !>>(), 2);

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