交换两个数字的值(Swap)

1.
#include<stdio.h>
//当实参传给形参的时候
//形参是实参的一份临时拷贝
//对形参的修改不会改变实参
void Swap(int *px,int *py)//无返回值
{
 int tmp = *px;
 *px = *py;
 *py = tmp;
}
//x，y叫形参
int main()
{
 int a = 10;
 int b = 20;
 Swap(&a, &b);
 printf("%d %d", a, b);
 return 0;
}
//a和b是实参

2.
#include<stdio.h>
int main(void)
{
 int a,b,temp;
 scanf("%d %d",&a,&b);
 temp = a;
 a = b;
 b = temp;
 printf("%d %d",a,b);
 return 0;
}
3.
#include<stdio.h>
int main(void)
{
 int a,b,temp;
 scanf("%d %d",&a,&b);
    temp = a;
 a = b;
 b = temp;
 printf("%d %d",a,b);
 return 0;
}

4.
#include<stdio.h>
int main(void)
{
 int a,b;
 scanf("%d %d",&a,&b);
 a=a+b;
 b=a-b;
 a=a-b;
 printf("%d %d",a,b);
 return 0;
}