【C语言】两个指针（地址）相减

#include <stdio.h>

int main()
{
    int a[9]={1,2,3,4,5,6,7,8,9};
    char  *p,*q;
    int *p2,*q2;
    p=(char*)a;
    q=(char*)&a[2];

    printf("p=%08X q=%08X a[%d]=%d\n",p,q,q-p,a[q-p]);
    //结果为：x,x+8,8/sizeof(char),a[8]=9
    p2=a;
    q2=&a[2];

    printf("p2=%08X q2=%08X a[%d]=%d\n",p2,q2,q2-p2,a[q2-p2]);
    //结果为：x,x+8,8/sizeof(int),a[2]=3
    getchar();
    return 0;
}