Struct Initialization

I have searched but am unable to come up with a specific answer. What is the best or most efficient way to initialize a struct? Here is what the struct looks like that I am currently dealing with.

Code:

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typedef struct id3v1
{
        char tag[3];
        char title[30];
        char artist[30];
        char album[30];
        char year[4];
        char comment[29];
        char track;
        char genre;
}        id3v1;

id3v1 id3v1_h;

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So I have been doing this:

Code:

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        for (i = 0; i < sizeof(id3v1_h); i++)
                id3v1_h.tag[i] = 0;

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But is this bad because it assumes that all of the variables are stored contiguously, or is it safe to assume this because that is the nature of structs?

Quote:

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But is this bad because it assumes that all of the variables are stored contiguously, or is it safe to assume this because that is the nature of structs?

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There may be padding, though how that affects your code I am not very sure. You could just write:

Code:

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id3v1 id3v1_h = {{0}, {0}, {0}, {0}, {0}, {0}, 0, 0};

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which really would be initialisation instead of assignment.

Right on, thats what I was looking for. I took care of the padding already. Thank you.

I'm getting a problem I have gotten before but I never knew how to exactly solve it.

Code:

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Error        1        error LNK2005: _id3v1_h already defined in check.obj        main.obj       
Error        2        fatal error LNK1169: one or more multiply defined symbols found        C:\Users\Ben\Desktop\Music Organizer\Debug\Music Organizer.exe

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Not sure why I get this. From the message it seems like a multi-declaration. Heres the format of my files.

main.c

Code:

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#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include "id3.h"

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check.c

Code:

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#include <windows.h>
#include <stdio.h>
#include "id3.h"

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id3.h

Code:

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#ifndef ID3_H
#define ID3_H

#pragma pack(push, 1)
typedef struct id3v1 
{
        char tag[3];
        char title[30];
        char artist[30];
        char album[30];
        char year[4];
        char comment[29];
        char track;
        char genre;
}        id3v1;
#pragma pack(pop)

id3v1 id3v1_h = {{0}, {0}, {0}, {0}, {0}, {0}, 0, 0};

int has_id3v1(char filename[]);

#endif

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Can you not initialize in header files or something?

Would padding be an issue if he used this command? This command would be shorter if he had a structure with many members.

memset(&id3v1_h, 0, sizeof(struct id3v1));

I am sure I could do something similar to that, it'd just be nice if I could keep the initialization with the declaration in the header file.

That would work because I removed the padding.