程序代码：

#include <stdio.h>

void changevalue(int *,int *);/*交换值*/
void changeaddress(int *,int *);/*交换地址*/

int main(void)
{
int *p,*q,a=1,b=2;
p=&a;q=&b;
printf("before changed: *p=%d,*q=%d,&p=%d,&q=%d",*p,*q,p,q);
printf("\nchange value:\n");
changevalue(p,q);
printf("\nafter changed: *p=%d,*q=%d,&p=%d,&q=%d",*p,*q,p,q);
a=1;b=2;/*重置a,b,p,q的值*/
p=&a;q=&b;
printf("\n\nbefore changed: *p=%d,*q=%d,&p=%d,&q=%d",*p,*q,p,q);
printf("\nchange address:\n");
changeaddress(p,q);
printf("\n\nbefore changed: *p=%d,*q=%d,&p=%d,&q=%d",*p,*q,p,q);
return 0;
}

void changevalue(int *x, int *y)
{
int z;
z=*x;*x=*y;*y=z;
printf("inside(changevalue): x=%d,y=%d,&x=%d,&y=%d",*x,*y,x,y);
}

void changeaddress(int *x, int *y)
{
int *z;
z=x;x=y;y=z;
printf("inside(changeaddress): x=%d,y=%d,&x=%d,&y=%d",*x,*y,x,y);
}