C结构体指针访问结构成员 

 1 #include <stdio.h>
 2 
 3 struct Payload {
 4     char* title;
 5     char* data;
 6 };
 7 
 8 char* extractData(struct Payload *payload);
 9 
10 int main(int argc, char const *argv[])
11 {
12     struct Payload payload;
13     
14     payload.title = "content-type";
15     payload.data = "text/html";
16 
17     char* data = extractData(&payload);
18     printf("%s\n", data);
19 
20     return 0;
21 }
22 
23 
24 char* extractData(struct Payload *payload) {
25     if (NULL == payload) {
26         return 0;
27     }
28     
29     return payload->data;
30 }

 

程序2：

#include <stdio.h>

struct User
{
    char* name;
    int age;
};
    

char* name(struct User *user) {
　　 // 传地址，访问成员需要用 ->
    return user->name;
}

char* another_name(struct User *user) {
　　// 或者 dereference 后，得到结构体然后用 .
    return (*(user)).name;
}

void main() {
    struct User user = {"h", 11};
    char* real_name = name(&user);
    printf("%s\n", real_name);

    printf("================\n");

    char* another_real_name = another_name(&user);
    printf("%s\n", another_real_name);

    printf("%zu\n", sizeof(real_name));
}

 

指针的size 与指向位置实际存储大小无关，而是与操作系统有关，64位机器， 返回8， 32位机器返回4；

 

posted @ 2021-08-22 19:18  Joynic  阅读(600)  评论(0)  编辑  收藏  举报