如何测试一个值是否在一个范围内? [英] How can I test if a value lies within a Range?

问题描述

我希望能够创建一个 Range 然后测试变量是否包含在该范围内.看起来像这样的东西:

I'd like to be able to create a Range and then test if a variable is contained in that range. Something that looks like this:

fn main() {
    let a = 3..5;
    assert!(a.contains(4));
}

现在，我看到的唯一明显的事情是使用 Iterator::any.这很丑陋，因为它需要 O(1) 操作并使其成为 O(n):

Right now, the only obvious thing I see is to use Iterator::any. This is ugly because it would take an O(1) operation and make it O(n):

fn main() {
    let mut a = 3..5;
    assert!(a.any(|v: i32| v == 4));
}

推荐答案

从 Rust 1.35 开始，原始代码将几乎¹ 使用 按原样编译="https://doc.rust-lang.org/std/ops/struct.Range.html#method.contains" rel="noreferrer">Range::contains:

As of Rust 1.35, the original code will almost¹ compile as-is using Range::contains:

fn main() {
    let a = 3..5;
    assert!(a.contains(&4));
}

¹ 将 &4 而不是 4 传递给 contains().

¹ Passing &4 instead of 4 to contains().

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