const保护指针

#include <iostream>
using namespace std;
int main()
{
    int a = 10, b = 5;
    const int *p1 = &a;
    // *p1 = 4;       //不合法
    p1 = &b;        //合法
    cout << "*p1=" << *p1 << endl;
    
    int * const p2 = &a;
    *p2 = 6;       //合法
    cout << "a=" << a << endl;
    //p2 = &b;       //不合法
    
    int &c = a;
    c = 32;      //合法
    cout << "a=" << a << endl;
    const int &d = a;
    d = 44;     //不合法
    return 0;
}