c++二级指针

如果要通过函数改变一个指针的值，要往函数中传入指针的指针
如果要通过函数改变一个变量的值，那就要往函数中传入这个变量的地址

改变a的值和b的值

#include <iostream>using namespace std;void swap(int* a, int* b) {int temp = *a;*a = *b;*b = temp;
}int main() {int a = 10;int b = 20;int* pa = &a;int* pb = &b;cout << a << endl; // 10cout << b << endl; // 20//需要传入a和b的地址swap(pa,pb);cout << "-------swap()--------" << endl;cout << a << endl; // 10cout << b << endl; // 20return 0;
}

改变pa的值和pb的值

#include <iostream>using namespace std;void changepoint(int** ppa, int** ppb) {int* temp = *ppa;   //*ppa=1000=*1090=*(&pa)=pa*ppa = *ppb;*ppb = temp;
}int main() {int a = 10;int b = 20;int* pa = &a;int* pb = &b;cout << *pa << endl; // 10cout << *pb << endl; // 20//需要传入pa和pb的地址changepoint(&pa, &pb);cout << "-------changepoint()--------" << endl;cout << *pa << endl; // 10cout << *pb << endl; // 20return 0;
}