pointer3.c

Linux 下 C 库及常用 系统调用的使用事例

#include <stdio.h>

/*交换函数，其形参为指针*/
void swap(int *p1, int *p2)
{
	int temp;
	/*交换指针单元所指的值*/
	temp = *p1;
	*p1 = *p2;
	*p2 = temp;
}

int main()
{
	int a,b;
	int *p1, *p2;
	a = 10; b = 20;
	/*指针赋初值，分别指向变量a和b的地址*/
	p1 = &a;
	p2 = &b;
	printf("before chaning:\n");
	printf("a = %d, b = %d\n",a, b);
	/*调用函数swap，其实参为指针*/
	swap(p1, p2);
	printf("after chaning:\n");
	/*函数调用后，能够改变实参的值*/
	printf("a = %d, b = %d\n",a, b);
	printf("*p1 = %d, *p2 = %d\n",*p1, *p2);
}