> For the complete documentation index, see [llms.txt](https://docs.1l.lol/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.1l.lol/complexity-debug/exceptions.md).

# 异常处理

### 什么是异常

程序运行中出现的非正常情况（如除以 0、数组越界、内存不足）称为异常。异常处理让程序在出错时不直接崩溃，而是跳转到处理代码。

### try-catch 结构

```cpp
#include <iostream>
#include <stdexcept>
using namespace std;

int main() {
    try {
        int a = 10, b = 0;
        if (b == 0) throw runtime_error("除数不能为 0");
        cout << a / b;
    } catch (const runtime_error &e) {
        cout << "捕获异常：" << e.what() << endl;
    } catch (...) {          // 捕获任意类型异常
        cout << "未知异常" << endl;
    }
    cout << "程序继续运行" << endl;
    return 0;
}
```

### 关键字

* `try`：包裹可能出错的代码
* `throw`：抛出异常
* `catch`：捕获并处理异常

### 常见异常类型（）

`runtime_error`、`logic_error`、`out_of_range`、`invalid_argument` 等。

### 使用建议

* 异常处理有性能开销，竞赛中一般用于简单场景。
* 更常见的是用条件判断（如提前 return）来避免错误。
* catch 按从具体到一般的顺序书写。


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