指向指针的指针，交换指针的值

交换指针的值
法二—通过二级指针实现

代码如下：

#include<iostream>
using namespace std;

//此函数用于交换指针的值，通过二级指针实现
void swap(int **ptr1, int **ptr2)//ptr先于左边第一个*结合成为一个指针
{                               //再看它指向的对象是类型是int *类型即指针，所以它是一个指向指针的指针。
    int *temp = *ptr1;          
    *ptr1 = *ptr2;
    *ptr2 = temp;
}

int main()
{
    int val1 = 3;
    int val2 = 4;
    int *p1 = &val1;
    int *p2 = &val2;
    cout<<"交换之前: "<<endl;
    cout<<"p1 = "<<p1<<" *p1 = "<<*p1<<endl;
    cout<<"p2 = "<<p2<<" *p2 = "<<*p2<<endl;

    swap(p1, p2);

    cout<<"交换之后: "<<endl;
    cout<<"p1 = "<<p1<<" *p1 = "<<*p1<<endl;
    cout<<"p2 = "<<p2<<" *p2 = "<<*p2<<endl;

    return 0;
}

结果如下：