排序a和b的大小顺序 (用指针)

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int main()
{
	int* p1, * p2, *p, a=0, b=0;
	scanf("%d %d", &a,&b);
	p1 = &a;
	p2 = &b;
	if(a<b)
		{p = p1; p1 = p2; p2 = p;}			//p1 p2指向交换，a b值不变
	printf("a=%d,b=%d\n", a, b);
	printf("max=%d,min=%d\n",*p1,*p2 );


	if (a < b)
		swap(p1, p2);

	return 0;
}

					// &a		&b
void swap(int* p1, int* p2)
{
	int temp;
	temp = *p1;
	*p1 = *p2;
	*p2 = temp;				//a b值交换了，p1 p2指向不变
}

错误写法

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int main()
{
	int* point1, * point2, a=0, b=0;
	scanf("%d %d", &a,&b);
	point1 = &a;
	point2 = &b;
	printf("a=%d,b=%d\n", a, b);
	if (a < b)		
		swap(point1, point2);
	printf("max=%d,min=%d\n",*point1,*point2);

	return 0;
}

					// &a		&b
void swap(int* p1, int* p2)
{
	int *p;
	p = p1;
	p1 = p2;
	p2 = p;				//交换了形参的指向，但无法带回实参！
}