1. panic异常

可以配置在release版本中，发生panic时是否中止运行

cargo.toml文件中

[package]
name = "demo"
version = "0.1.0"
edition = "2021"# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html[dependencies][profile.release]
panic= 'abort'

1.1自定义panic

测试代码：

fn main(){panic!("不可恢复异常！");
}

运行结果：

thread 'main' panicked at '不可恢复异常！', src/main.rs:6:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

1.2 越界panic

测试代码：

fn main() {let v = vec![1, 2, 3];v[4];
}

运行结果：

thread 'main' panicked at 'index out of bounds: the len is 3 but the index is 4', src/main.rs:7:1
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

1.3 显示调用栈

先设置环境变量RUST_BACKTRACE=1后，再运行就可以显示调用栈信息

xuanwenchao@bogon demo % export RUST_BACKTRACE=1
xuanwenchao@bogon demo % cargo run              Finished dev [unoptimized + debuginfo] target(s) in 0.00sRunning `target/debug/demo`
thread 'main' panicked at 'index out of bounds: the len is 3 but the index is 4', src/main.rs:7:1
stack backtrace:0: rust_begin_unwindat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/std/src/panicking.rs:575:51: core::panicking::panic_fmtat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/panicking.rs:64:142: core::panicking::panic_bounds_checkat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/panicking.rs:147:53: >::indexat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/slice/index.rs:260:104: core::slice::index:: for [T]>::indexat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/slice/index.rs:18:95:  as core::ops::index::Index>::indexat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/alloc/src/vec/mod.rs:2727:96: demo::mainat ./src/main.rs:7:17: core::ops::function::FnOnce::call_onceat /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/ops/function.rs:507:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
xuanwenchao@bogon demo % 

pub enum Result {/// Contains the success value#[lang = "Ok"]#[stable(feature = "rust1", since = "1.0.0")]Ok(#[stable(feature = "rust1", since = "1.0.0")] T),/// Contains the error value#[lang = "Err"]#[stable(feature = "rust1", since = "1.0.0")]Err(#[stable(feature = "rust1", since = "1.0.0")] E),
}

use std::fs::File;
fn main() {let mut f = match File::open("test.txt") {Ok(f) => f,Err(e) => {panic!("打不开文件！{}", e)}};
}    

thread 'main' panicked at '打不开文件！No such file or directory (os error 2)', src/main.rs:9:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

use std::fs::File;
use std::io::{ErrorKind, Read};
fn main() {let mut f = match File::open("test.txt") {Ok(f) => f,Err(e) => match e.kind() {ErrorKind::NotFound => match File::create("test.txt") {Ok(f1) => f1,Err(e1) => panic!("创建文件也不行！{:?}", e1),},_other_error=>panic!("其它原因，不处理！")},};let mut ss = String::new();f.read_to_string(&mut ss).expect("error!");
}    

use std::fs::File;
use std::io::{self, Read};fn main() {let user_name = match read_username_from_file() {Ok(name) => println!("用户名：{}", name),Err(e) => panic!("读取失败！"),};
}fn read_username_from_file() -> Result {let f = File::open("test.txt");let mut f = match f {Ok(f1) => f1,Err(e1) => return Err(e1),};//查找用户名的位置，然后读取，此处省略let mut s = String::new();f.read_to_string(&mut s)?;Ok(s)

    let f = File::open("test.txt");let mut f = match f {Ok(f1) => f1,Err(e1) => return Err(e1),};

    let f = File::open("test.txt")?;

fn read_username_from_file() -> Result {File::open("test.txt")?.read_to_string(&mut s)?;Ok(s)
}