> 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/basics/data-types.md).

# 基本数据类型

### 四种基本类型

| 类型    | 关键字         | 说明                | 例子                    |
| ----- | ----------- | ----------------- | --------------------- |
| 整型    | `int`       | 整数，约 ±21 亿        | `int a = 10;`         |
| 长整型   | `long long` | 更大范围的整数           | `long long b = 1e18;` |
| 单精度实型 | `float`     | 小数，约 6\~7 位有效数字   | `float f = 3.14f;`    |
| 双精度实型 | `double`    | 小数，约 15\~16 位有效数字 | `double d = 3.14159;` |
| 字符型   | `char`      | 单个字符，用单引号         | `char c = 'A';`       |
| 布尔型   | `bool`      | true / false      | `bool ok = true;`     |

### 取值范围（常见）

| 类型           | 范围                        |
| ------------ | ------------------------- |
| int          | -2147483648 \~ 2147483647 |
| unsigned int | 0 \~ 4294967295           |
| long long    | ≈ -9.2×10¹⁸ \~ 9.2×10¹⁸   |
| char         | -128 \~ 127               |

### 使用注意

* 数据超过 int 范围会溢出，应改用 `long long`。
* 小数尽量用 `double`，精度更高。
* 字符用**单引号** `'A'`，字符串用**双引号** `"A"`。

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

int main() {
    int i = 100;
    long long big = 1234567890123LL;
    double pi = 3.1415926;
    char grade = 'A';
    bool pass = true;
    cout << i << " " << big << " " << pi << " "
         << grade << " " << pass << endl;  // bool 输出 1
    return 0;
}
```


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