> 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/char-array.md).

# 字符数组

### 字符数组基础

字符数组用于存放一串字符，以 `'\0'` 结尾：

```cpp
char s[10] = "hello";     // 5 个字符 + 结束符
char t[] = {'a', 'b', 'c', '\0'};
```

### 字符与数字的转换（重点）

数字字符与其数值相差 `'0'`（即 48）：

```cpp
char ch = '5';
int num = ch - '0';        // 5
int num2 = ch - 48;        // 等价写法

int x = 7;
char c = x + '0';          // '7'
```

大写字母与小写字母相差 32：

```cpp
char up = 'A' + 32;        // 'a'
char lo = 'a' - 32;        // 'A'
```

### 输入输出

```cpp
char s[100];
cin >> s;                  // 遇空格停止
cout << s;                 // 输出到 \0 为止
```

### 常见操作

```cpp
int n = strlen(s);         // 长度
s[0] = 'H';                // 修改某字符
strcpy(a, s);              // 复制
strcat(a, s);              // 拼接
```

### 与 string 的选择

* 需要字符数组 / 与 C 函数配合时用 `char[]`。
* 日常处理字符串优先用 `string`，更方便安全。


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