CODEWITHSUNDEEP
rust
Minh Triet
Minh Triet

Reputation: 1250

Replacing a variable in Rust with same value yields different result

I could not understand this code. How comes -a yields different result from -7?

fn main() {
    let a: i32 = 7; // or any other integer type
    let b = 4;
                
    assert_eq!((-a).rem_euclid(b), 1);
    assert_eq!(-7_i32.rem_euclid(4), -3);
    assert_eq!(-a, -7_i32);
}

Playground link: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=3147fbbf7aeeeff5510522f9af2d12f2

Upvotes: 0

Views: 97

Answers (1)

Emerson Harkin
Emerson Harkin

Reputation: 917

It's because -7_i32.rem_euclid(4) == -(7_i32.rem_euclid(4)). The unary negation has lower precedence than the method call.

Upvotes: 4

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