C语言完美演绎3-16

/* 范例：3-16 void指针 */

#include <stdio.h>

void main(void)

{

int a = 6838;

int *p;

printf("&p=%u :%d bytes\n", &p, sizeof(&p));

p = &a;

printf("*p = %d p = %u\n", *p, p);

printf(" a = %d &a = %u", a, &a);

printf("\n-------------------------------------");

/*-------------------------------------------------------------------------*/

int i;

float r;

void *poin = &i; /* 取i的地址存放到指针变量poin中 */

*(int *)poin = 2; /* 设定void类型指针变量poin指向的变量(i)为2 */

poin = &r; /* 取浮点变量r的地址存放到poin，因此目前poin指向变量r */

*(float *)poin = 2.3; /* 按照地址操作值, 将r值设定为2.3 */

printf("\n*poin = %d poin = %u\n", *(int *)poin, poin);

printf("\n*poin = %f poin = %u\n", *(float *)poin, poin);

printf("i = %d &i = %u", i, &i);

getchar();

}

程序执行结果﹕

&p=6618620 :4 bytes

*p = 6838 p = 6618624

a = 6838 &a = 6618624

---

*poin = 1075000115 poin = 6618612

*poin = 2.300000 poin = 6618612

i = 2 &i = 6618616