1、測試代碼:
#include<stdio.h>
#include<string.h>
struct DATA
{
int year;
int month;
int day;
};
struct TEST
{
int a;
char b;
};
int main(void)
{
struct DATA data1;
void *p;
data1.year = 2020;
data1.month = 4;
data1.day = 2;
p = &data1;
struct DATA *data2;
data2 = p ;
printf("data2 : year =%d, month =%d, day =%d\r\n ",data2->year,data2->month,data2->day);
data2->day = 5;
printf("data2 : year =%d, month =%d, day =%d\r\n ",data2->year,data2->month,data2->day);
printf("data1 : year =%d, month =%d, day =%d\r\n ",data1.year,data1.month,data1.day);
struct TEST *test;
test = p ;
printf("test : a =%d, b=%d\r\n",test->a,test->b);
printf("test : a =%d, b=%d\r\n",test->a,*(test+1));
printf("test : a =%d, b=%d c=%d\r\n",test->a,*(test+1),*(test+2));
return 0 ;
}
2、輸出結果:
3、結論:
1、空指針可以被/給任何類型的指針賦值,指針賦值的實質是傳遞地址。
2、同類型的結構體指針可以直接賦值也可以通過空指針作爲中轉。
3、不同類型的結構體指針可以通過空指針的中轉賦值,如果不同結構體的成員的類型和數量相同還好,如果不同,雖然能夠編譯過,但得到的值需謹慎對待。