C語言實現 用函數實現兩個數的交換

#include <stdio.h>
#include <stdlib.h>
int main()
{
 int a, b;
 int change_num(int a, int b);//聲明change_num函數
 printf("please enter two numbers:");
 scanf("%d,%d", &a, &b);
 change_num(&a,&b);//調用change_num函數
 printf("%d %d\n", a, b);
 system("pause");
 return 0;
}
int change_num(int *px, int *py)//定義change_num函數
{
 int temp;
 temp = *px;
 *px = *py;
 *py = temp;
}