Rust中的输入输出格式变化（非常详细）

1.字符类型输入，从键盘输入啥，输出就是啥。

use std::io;
fn main() {
let mut guess = String::new();
io::stdin().read_line(&mut guess).expect("Failed to read line");
println!("You guessed: {}",guess);
}
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2.输入整数字符类型，输出整数类型

use std::io::stdin;
fn main() {
    let mut input = String::new();
    stdin().read_line(&mut input)
        .ok()
        .expect("Failed to read line");  
    let i: i32 = match input.trim().parse() {
        Ok(num) => num,
        Err(_) => {
             println!("请输入整数，请勿输入无关符号！");
             return;
        }
    };
    println!("i: {i}");
}
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使用 trim() 去除多余的符号，例如回车号，然后使用 parse() 来做数据转换。

3.输入字符串[1,2,4,5,6],输出整型数组vec类型

use std::io::stdin;
fn main() {
    let mut vec:Vec<i32>=Vec::new();
    let mut input = String::new();
    stdin().read_line(&mut input)
        .ok()
        .expect("Failed to read line");

    let first_last_off: &str = &input[1..input.len() - 2];
    println!("{}", first_last_off);
    let v:Vec<&str> = first_last_off.split(',').collect();
    for i in v{
        let i:i32=match i.trim().parse(){
            Ok(num)=>num,
            Err(_)=>{
                println!("请输入整数，请勿输入无关符号！");
                return;
        }
    };
        vec.push(i);
}
}
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4.例子：求一个数组中次数大于n/3的数，返回数组

use std::io::stdin;
use std::collections::HashMap;

pub fn majority_element(nums: Vec<i32>)->Vec<i32>{
    let n=nums.len();
    let l=n/3;
    let mut V:Vec<i32>=Vec::new();
    let mut map=HashMap::new();
    for word in nums{
        let count =map.entry(word).or_insert(0);
        *count+=1;
    };
    println!("{:#?}",map);
    for (k,v) in map{
        if(v>l){
            V.push(k)
        }
    }
    V
}
fn main() {
    let mut vec:Vec<i32>=Vec::new();
    let mut num:Vec<i32>=Vec::new();
    let mut input = String::new();
    stdin().read_line(&mut input)
        .ok()
        .expect("Failed to read line");
    let first_last_off: &str = &input[1..input.len() - 2];
    println!("{}", first_last_off);
    let v:Vec<&str> = first_last_off.split(',').collect();
    for i in v{
        let i:i32=match i.trim().parse(){
            Ok(num)=>num,
            Err(_)=>{
                println!("请输入整数，请勿输入无关符号！");
                return;
        }
    };
        vec.push(i);
}
num=majority_element(vec);
println!("{:?}",num)
}
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5.各种类型的互相转换

let int_value = 5;
//整型转字符串
let string_value = int_value.to_string();

//字符串转32位有符号整型
let back_int = string_value.parse::<i32>().unwrap();

// 字符串转32位无符号整型
let back_int = string_value.parse::<u32>().unwrap();

//字符串转16位有符号整型
let back_int = string_value.parse::<i16>().unwrap(); 
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