变量3：exercises/variables/variables3.rs

题目

rust

// variables3.rs
//
// Execute `rustlings hint variables3` or use the `hint` watch subcommand for a
// hint.

// I AM NOT DONE

fn main() {
    let x: i32;
    println!("Number {}", x);
}

题目解析

编译错误信息显示如下：

txt

⚠️  Compiling of exercises/variables/variables3.rs failed! Please try again. Here's the output:
error[E0381]: used binding `x` isn't initialized
  --> exercises/variables/variables3.rs:10:27
   |
9  |     let x: i32;
   |         - binding declared here but left uninitialized
10 |     println!("Number {}", x);
   |                           ^ `x` used here but it isn't initialized
   |
   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider assigning a value
   |
9  |     let x: i32 = 0;
   |                +++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0381`.

在这个练习中，我们先是创建了一个变量绑定let x: i32;，然后尝试使用它，但是错误信息提示我们定义了绑定，但是我们没有对x进行初始化，自然是无法打印一个不存在的东西。

所以如错误提示那样，我们需要给变量x赋值，比如let x: i32 = 0;

rust

fn main() {
    let x: i32; 
    let x: i32 = 0; 
    println!("Number {}", x);
}

笔记

变量需要先进行初始化，才能使用

参考资料

变量先声明

变量3：exercises/variables/variables3.rs ​

题目 ​

题目解析 ​

参考资料 ​

变量3：exercises/variables/variables3.rs

题目

题目解析

参考资料