How access to struct in .h , from my principal program

[robintux]

i'm writing a header , from define a struct.

The question is , how declare this struct in my main.c .

function.c

 struct data{
       size_t n;
       gsl_vector  *y;
     };

function.h

/*here should be the struc data*/
?????

main.c

#include "function.h"
	struct data d = { n, y 	};

Errors :

error: variable `d' has initializer but incomplete type

[Banfa]

Move what you have posted as being in function.h

struct data{
       size_t n;
       gsl_vector  *y;
     };

into function.h. Then include function.h in both main.c and function.c

Do you know about multiple inclusion protection?

/* Nothing here but comments */
#ifndef FUNCTION_H_INCLUDED
#define FUNCTION_H_INCLUDED

/* All the declarations in the header file */


#enndif /* FUNCTION_H_INCLUDED*/
/* Nothing here but comments */

This stops redefinition of type errors if headers get included into source files more than once.

[donbock]

That should be "Move what you have posted as being in function.c into function.h."

[robintux]

That should be "Move what you have posted as being in function.c into function.h."

right donbock , i read multiple inclusion protection .
Another way ????

[donbock]

"I read multiple inclusion protection. Another way ????"

I don't understand your question. Please elaborate.

By the way, the cool pedantic term for "multiple inclusion protection" is idempotency. This word refers to an operation (in this case #include) that produces the same result no matter how many times it is invoked. Casually written header files are not idempotent because C syntax does not allow multiple definitions of the same entity even if those definitions are all the same.

[robintux]

"I read multiple inclusion protection. Another way ????"

I don't understand your question. Please elaborate.

In the post of banfa

"Do you know about multiple inclusion protection?"

I know it's not "multiple inclusion protection"