return 语句

#include <iostream>using namespace std;void do_a(){cout << "b" << endl;cout << "bb" << endl;// return; // 提前return，return就是结束，cout << "bbb" << endl;}//void表示返回值是void，void返回值就是没有返回值，void swap(int &v1, int &v2)  // swap是用来交换，{if (v1 == v2)return;//提前return，int tmp = v2;v2 = v1;v1 = tmp;return; // 可以省略，}int add(const int &a, const int &b){int sum = 0;sum = a + b;return sum; // 这个地方必须有返回值，}int main(){cout << "这是main：" << endl;do_a();cout << "这是main end。" << endl;int a = 2, b = 4;cout << "交换前a = " << a << ", b = " << b << endl;swap(a, b);cout << "交换后：a = " << a << ", b = " << b << endl;return 0; // 返回0表示正常结束没有出错，}