函式

fn gcd(a: u32, b: u32) -> u32 {
    if b > 0 {
        gcd(b, a % b)
    } else {
        a
    }
}

fn main() {
    println!("gcd: {}", gcd(143, 52));
}
This slide should take about 3 minutes.
  • 宣告參數後面接有型別 (與某些程式設計語言相反)，然後才是傳回型別。
  • The last expression in a function body (or any block) becomes the return value. Simply omit the ; at the end of the expression. The return keyword can be used for early return, but the "bare value" form is idiomatic at the end of a function (refactor gcd to use a return).
  • 某些函式沒有回傳值，會傳回 () 這個「單位型別」。如果省略 -> () 傳回型別，編譯器則會推斷出這點。
  • Overloading is not supported -- each function has a single implementation.
    • 請一律採用定量參數。系統不支援預設引數。如要支援可變參數函式，請使用巨集。
    • Always takes a single set of parameter types. These types can be generic, which will be covered later.