#include <stdio.h>

int main()
{
    int number = 9;
    int *pnumber = &number;

    const int *pnumber2 = NULL; // 指向常量的指针
    pnumber2 = &number;
    // *pnumber2 = 10; // error

    int *const pnumber3 = NULL; // 常量指针
    // pnumber3 = &number; // error

    printf("number address: %p value: %d\n", &number, number);
    printf("pnumber address: %p value: %p pointer: %d\n", &pnumber, pnumber, *pnumber);
}