rust - 尝试使用增量运算符时编译错误

Question

在业余项目的工作中，我尝试使用增量运算符，如下所示:

fn main() {
    let mut my_var = 5;
    my_var++;
}

并收到以下错误:

error: expected expression, found `+`
 --> src\main.rs:3:12
  |
3 |     my_var++;
  |            ^

我的代码有什么问题？

Answer 1

递增 (++) 和递减 (--) 运算符在 Rust 中不支持。

来自 Rust's FAQ :

Why doesn't Rust have increment and decrement operators?
Preincrement and postincrement (and the decrement equivalents), while convenient, are also fairly complex. They require knowledge of evaluation order, and often lead to subtle bugs and undefined behavior in C and C++. x = x + 1 or x += 1 is only slightly longer, but unambiguous.