按值传递时，您正在转让值的所有权.不需要变量的副本-首先main拥有它，然后reset拥有它，然后消失了 ¹ .

When you pass by value, you are transferring ownership of the value. No copies of the variable are required — first main owns it, then reset owns it, then it's gone¹.

在Rust中，当您拥有一个变量的所有权时，您可以控制它的可变性.例如，您可以执行以下操作:

In Rust, when you have ownership of a variable, you can control the mutability of it. For example, you can do this:

let a = [1, 2, 3, 4, 5];
let mut b = a;

您也可以在reset内部执行相同的操作，尽管我不会 执行此操作，而是希望在函数签名中使用mut:

You could also do the same thing inside of reset, although I would not do this, preferring to use the mut in the function signature:

fn reset(b: [u32; 5]) {
    let mut c = b;
    c[0] = 5;
}

另请参阅:

• 通过可变值传递的惯用方式是什么?
• 将"mut"放置到在变量名之前和:"之后?

• What's the idiomatic way to pass by mutable value?
• What's the difference between placing "mut" before a variable name and after the ":"?

1 —在此特定情况下，您的类型是[i32; 5]，它实现了Copy特性.如果您在授予reset所有权后尝试使用a，则将创建一个隐式副本. a的值将保持不变.

1 — In this specific case, your type is an [i32; 5], which implements the Copy trait. If you attempted to use a after giving ownership to reset, then an implicit copy would be made. The value of a would appear unchanged.