指针 p238

/*swap3.c-- 使用指针完成交换*/
#include <stdio.h>
int interchange (int *u,int *v);
int main ()
{
int x=5,y=10;
printf ("Originally x=%d and y= %d .\n",x,y);
interchange (&x,&y);
printf ("Now x=%d and y= %d .\n",x,y);
return 0;
 } 
 
 int interchange (int *u,int *v)
 {
  int temp;
  temp=*u;
  *u=*v;
  *v=temp;
 }