将具有位域和动态数据的结构复制到Char数组缓冲区中

Question

I have a struct like the following

struct Struct {
    int length; //dynamicTest length 
    unsigned int b: 1;
    unsigned int a: 1;
    unsigned int padding: 10;
    int* dynamicTest;
    int flag; 
}

I want to copy this into a char array buffer (to send over a socket). I'm curious how I would do that.

Answer 1

To be precise, you do this with memcpy , eg:

#include <string.h>
/* ... */
Struct s = /*... */;
char buf[1024]
memcpy(buf, &s, sizeof(s));
/* now [buf, buf + sizeof(s)) holds the needed data */

Alternatively you can avoid copying at all and view an instance of struct as an array of char (since everything in computer memory is sequence of bytes, this approach works).

Struct s = /* ... */;
const char* buf = (char*)(&s);
/* now [buf, buf + sizeof(s)) holds the needed data */

If you are going to send it over the network, you need to care of byte order, int size and many other details.

Copying bit fields present no problem, but for dynamic fields, such as your char* this naive approach won't work. The more general solution, that works with any other types is serialization .