01-参数解析

Thu, 20 Aug 2026 21:20:00 +0800

译文 · 基于 Rust By Example

原文链接: https://doc.rust-lang.org/stable/rust-by-example/std_misc/arg/matching.html

参数解析

可以用模式匹配来解析简单的参数：

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use std::env;

fn increase(number: i32) {
 println!("{}", number + 1);
}

fn decrease(number: i32) {
 println!("{}", number - 1);
}

fn help() {
 println!("usage:
match_args <string>
 Check whether given string is the answer.
match_args {{increase|decrease}} <integer>
 Increase or decrease given integer by one.");
}

fn main() {
 let args: Vec<String> = env::args().collect();

 match args.len() {
 // 没有传入参数
 1 => {
 println!("My name is 'match_args'. Try passing some arguments!");
 },
 // 一个传入参数
 2 => {
 match args[1].parse() {
 Ok(42) => println!("This is the answer!"),
 _ => println!("This is not the answer."),
 }
 },
 // 传入一条命令和一个参数
 3 => {
 let cmd = &args[1];
 let num = &args[2];
 // 解析数字
 let number: i32 = match num.parse() {
 Ok(n) => {
 n
 },
 Err(_) => {
 println!("error: second argument not an integer");
 help();
 return;
 },
 };
 // 解析命令
 match &cmd[..] {
 "increase" => increase(number),
 "decrease" => decrease(number),
 _ => {
 println!("error: invalid command");
 help();
 },
 }
 },
 // 所有其他情况
 _ => {
 // 显示帮助信息
 help();
 }
 }
}

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$ ./match_args Rust
This is not the answer.
$ ./match_args 42
This is the answer!
$ ./match_args do something
error: second argument not an integer
usage:
match_args <string>
 Check whether given string is the answer.
match_args {increase|decrease} <integer>
 Increase or decrease given integer by one.
$ ./match_args do 42
error: invalid command
usage:
match_args <string>
 Check whether given string is the answer.
match_args {increase|decrease} <integer>
 Increase or decrease given integer by one.
$ ./match_args increase 42
43

07-程序参数 on 编程那些事儿

01-参数解析

参数解析