> 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/strings/string-reverse.md).

# 字符串逆序

### 方法一：像字符数组一样倒序输出

```cpp
string s;
cin >> s;
for (int i = s.size() - 1; i >= 0; i--)
    cout << s[i];
```

### 方法二：使用 reverse

```cpp
#include <algorithm>
string s = "hello";
reverse(s.begin(), s.end());
cout << s;        // olleh
```

### 方法三：递归（原来是错的）

原笔记用 `!` 作为结束标志，只对特定输入成立，应改为按长度判断：

```cpp
void printReverse(string &s, int i) {
    if (i >= (int)s.size()) return;   // 正确的终止条件
    printReverse(s, i + 1);
    cout << s[i];
}
```

### 字符数组版

```cpp
char s[100];
cin >> s;
for (int i = strlen(s) - 1; i >= 0; i--)
    cout << s[i];
```

### 要点

* 终止条件要基于真实长度，不要依赖某个特殊字符。
* 日常优先用 `reverse`，简洁且不易出错。


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