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if-statementrustconditional-operator

How can I port C++ code that uses the ternary operator to Rust?

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

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

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

Solution

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

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

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

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

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

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