C 语言：将数据从一个 typedef 结构复制到另一个并返回一个值

Question

I am new in C & I am currently working with structures. I am stuck & I would be very grateful if somebody came to my rescue. So I have a function to write input data from the main module to the sub-module. It should return 0 if it writes successfully, & 1 if it doesn't succeed. I have been reading widely but I am still unsure whether to use memcpy or not. Then, on the return value I have read that memcpy returns 0 if the operation was successful and 1 if it was not. Here is that part of my code:

typedef struct {
    UINT32 carnum_n;
    UINT32 carnum_k;
    UINT32 results[30];
    UINT32 feedback[30];  
    UINT32 errors[30];
} MAIN;

typedef struct {
   UINT32 carnum_n;
   UINT32 carnum_k;
   UINT32 feedback[30];
} SETTING;

/* function to copy the data from the main to the sub-module */    
UINT32 Write( MAIN *data, SETTING *info)
{
   sc_memcpy ( &info->carnum_k, &data->carnum_k, sizeof (SETTING));
   sc_memcpy ( &info->feedback, &data->feedback, sizeof (SETTING));  //copies the array
}

1. Please tell me, is this correct? If not, what is the correct way to write it? Or what other alternatives do I have?
2. As I have an array as well, how should I go about it? What changes when I have to save say upto fb[10] from the main module to the sub-module?
3. How do I incoorporate the return condition, given that I should seemingly write ONE line of code to copy each type of data from the main module's table to the sub-module's input table?

I really want to get this right. Thanks in Advance:)

Answer 1

Question 1, your code is not correct.

When copy carnum_k , the sizeof(SETTING) is wrong. sizeof (SETTING) means the size of all data in SETTING structure. But you just need copy carnum_k , so you need provide the size of carnum_k , which is sizeof (UINT32) , UINT32 is the type of carnum_k .

memcpy ( &info->carnum_k, &data->carnum_k, sizeof (UINT32));

You can also just write an assignment info->carnum_k = data->carnum_k .

The copy of feedback has two problem.

1. sizeof (SETTING) is wrong just like when you copy carnum_k . You can use sizeof(UINT32 [30]) , UINT32 [30] is the type of feedback .
2. info->feedback is an array address, so no need &info->feedback , just info->feedback .

memcpy(info->feedback, data->feedback, sizeof(UINT32 [30]));

Question 2. I think you mean you may want just copy part of feedback .

When you copy memory you need figure out src memory address, dest memory address, and the size of memory you want to copy.

so if you want copy from feedback[2] to feedback[10] .

• source address is &(data->feedback[2])
• dest address is &(info->feedback[2]) .
• From 2 to 10, there is 9 value you want to copy, so the total size is 9 * sizeof(UINT32)

memcpy(&(info->feedback[2]), &(data->feedback[2]), 9*sizeof(UINT32));

Question 3.

I don't known the answer.