use std::fs::File;use std::io::Read;fn read_file(path: &str) -> Result<String, std::io::Error> { let mut file = File::open(path)?; let mut contents = String::new(); file.read_to_string(&mut contents)?; Ok(contents)}1.2.3.4.5.6.7.8.9.read_file函数读取...
; // 读取文件的内容,可能会发生错误std::io::Error let content = std::fs::read_to_string(file)?; Ok(content) } 缺点: Box<dyn Error> 类型是动态类型,它的类型信息会在运行时丢失,会导致在处理错误时,无法根据类型来处理不同的错误情况 它不能包含错误码 由于Box<dyn Error> 类型只能存储一个...
#![allow(unused)] fn main() { use std::fs::File; use std::io; use std::io::Read; fn read_username_from_file() -> Result<String, io::Error> { let mut username_file = File::open("hello.txt")?; let mut username = String::new(); username_file.read_to_string(&mut username...
fnread_file_to_string(file_path:String)->Result<String, MyError>{letr= File::open(file_path.clone());matchr {Ok(mutfile) => {letmutcontents= String::new();letr2= file.read_to_string(&mutcontents);matchr2 {Ok(size) =>returnOk( contents),Err(e) =>returnErr(MyError::Common(for...
(.to_string()) } } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. Rust的异常体系中 std::error::Error,是一个核心Trait, 任何实现了该Trait的struct, 标准库都将自动为其实现From, 这样该struct就可以转换为Box<Error + 'a>...
fnread_text_from_file(path:&str)->Result<String,io::Error>{ letmutf=File::open(path)?; letmuts=String::new(); f.read_to_string(&muts)?; Ok(s) } fnmain(){ letstr_file=read_text_from_file("hello.txt"); matchstr_file{ ...
to_string()) } } fn main() { let result = divide(10.0, 2.0); match result { Ok(value) => println!("Result: {}", value), Err(error) => println!("Error: {}", error), } } 总结 本篇博客介绍了Rust的各种数据类型,包括布尔类型、整数类型、浮点类型、字符类型、元组、数组、字符串、...
error: could not compile `cargo_learn`. To learn more, run the command again with --verbose. 我们还可以使用match表达式来自定义对于返回值执行不同的操作: use std::fs::File; fn main() { let f = File::open("hello.txt"); let f = match f { ...
usestd::io;usestd::io::Read;usestd::fs::File;fnread_username_from_file() ->Result<String, io::Error> {letmutf = File::open("hello.txt")?;letmuts =String::new(); f.read_to_string(&muts)?;Ok(s) } 代码中第6行的?操作符会被展开成类似下面的代码: ...
use std::fs::File;use std::io::{self,Read};fnread_file()->Result<(),io::Error>{letmut file=File::open("file.txt")?;letmut contents=String::new();file.read_to_string(&mut contents)?;println!("文件内容:{}",contents);Ok(())}fnmain(){matchread_file(){Ok(_)=>println!("...