> 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/sequence.md).

# 顺序结构

### 什么是顺序结构

程序从上到下依次执行每一条语句，是三种基本结构中最简单的一种。

### 一条完整的顺序程序

输入 → 处理 → 输出。

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

int main() {
    // 1. 输入
    int a, b;
    cin >> a >> b;

    // 2. 处理
    int sum = a + b;
    int product = a * b;

    // 3. 输出
    cout << sum << endl;
    cout << product << endl;
    return 0;
}
```

### 复合语句与缩进

用一对花括号 `{ }` 把多条语句组成一个**复合语句（语句块）**。养成良好缩进习惯，便于阅读。

### 交换两个变量

```cpp
int a = 3, b = 5;
int t = a;   // 借助临时变量
a = b;
b = t;       // a=5, b=3
```


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