如何将使用三元运算符的C ++代码移植到Rust？ [英] How can I port C++ code that uses the ternary operator to Rust?

问题描述

如何将C ++代码移植到Rust：

How can I port this C++ code to Rust:

auto sgnR = (R >= 0.) ? 1. : -1.;

我见过一些匹配的例子关键字，但我不了解它的工作原理。

I have seen some examples with the match keyword, but I don't understand how it works.

推荐答案

Rust没有三元运算符，因为它不是必需的。一切都会达到一定的价值，并且 c 或 else 语句也不例外：

Rust does not have the ternary operator because it's not needed. Everything evaluates to some value, and if / else statements are no exception:

let r = 42.42;
let sgn_r = if r >= 0. { 1. } else { -1. };

您会注意到，我还将变量名更改为惯用的Rust。标识符使用 snake_case 。

You'll note that I've also changed your variable names to be idiomatic Rust. Identifiers use snake_case.

不要被混淆吗？ Rust 拥有的运算符。这是称为尝试运算符，用于传播错误。

Do not be confused by the ? operator that Rust does have. This is called the "try operator" and is used to propagate errors.

专门针对 this 代码，您可能应该使用 f64 :: signum ：

Specifically for this code, it's likely you should use f64::signum:

let r = 42.42_f64;
let sgn_r = r.signum();

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