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rust default parameter value

Sorann answered on May 26, 2023 Popularity 9/10 Helpfulness 3/10

answer rust default parameter value

rust default parameter value

Comment

Basically rust doesn't support default parameter value, but you can still do something equivalent with either of those two solutions

fn add(a: Option<i32>, b: Option<i32>) -> i32 {
    a.unwrap_or(1) + b.unwrap_or(2)
}
add(None, None) // return 3
add(None, 9) // return 10
add(7) // error, the None are required


// Or alternativelly
fn add(a: i32, b: i32) -> i32 {
    a + b
}
macro_rules! add {
    ($a: expr) => {
        add($a, 2)
    };
    () => {
        add(1, 2)
    };
}
add!() // return 3
add!(4) // return 6
add!(,9) // error, this can't be done with macro

Popularity 9/10 Helpfulness 3/10 Language rust

Source: stackoverflow.com

Tags: default rust

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