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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.

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Stepan Yakovenko Avatar asked Jul 14 '17 00:07

Stepan Yakovenko


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1 Answers

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. }; 

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(); 
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Shepmaster Avatar answered Oct 09 '22 01:10

Shepmaster