rust - 这段代码怎么编译通过?

Question

fn sum<T>(array: &[T]) -> T {     let mut sum: T = 0;     for i in array {       sum = sum + i;     }     return sum;  }

大概功能就是计算一个数组内的元素的和,怎么约束 T 让这段程序编译通过

Answer 1

use std::ops::Add;fn sum<T: Add<Output = T> + Default + Copy>(array: &[T]) -> T {    let mut sum: T = T::default();    for i in array {        sum = sum + *i;    }    return sum;}fn main() {    let array = [7, 2, 3, 4, 12];    println!("Result: {}", sum(&array))    // Result: 28}

Answer 2

use std::ops::Add;fn sum<T>(array: &[T])-> T  where  T: Add<Output = T> + Copy + Default,{  let mut sum: T = Default::default();  for i in array {    sum = sum + *i;  }  sum}