设计main函数，从键盘上输入两个整型变量a，b的值，交换它们的值并输出。

#include <iostream>
using namespace std;

int main() {
int a, b;
cout << "请输入两个整数a和b：" << endl;
cin >> a >> b;
cout << "交换前a=" << a << ", b=" << b << endl;
int temp = a;
a = b;
b = temp;
cout << "交换后a=" << a << ", b=" << b << endl;
return 0;
}