How to access a structure defined in a header file from an implementation file?

How do you access a struct say struct common, that is defined in a header file, in a .c file? We'll include the header file in the .c file and then can we directly use struct common C;?

header file-new_algo.h

      #ifndef NEW_ALGO_H_

       #define NEW_ALGO_H_
       #endif /* NEW_ALGO_H_ */

       struct common开发者_StackOverflow中文版{


        float count;
         //other variables

      };

main.c

 #include "new_algo.h"

  int main()
{
    typedef struct common myStruct;
    myStruct* S;

   S->count = 0;//when I do this segmentation fault occurs
   //this is the error I get in eclipse

/* Thread [1] 0 (Suspended : Signal : SIGSEGV:Segmentation fault)   
main() at E:/Namratha//trial/.settings/..\\src\\main.c:44 0x401443*/    

}

Hey, the fault error is not resulted from access control.

Before use struct varible, you should malloc space for it like

myStrcut *s = (myStrcut *)malloc(sizeof(myStruct))

then assign:

s->count = 0

Please have a try.

Yes, it's correct. Just include the header in the source file and create the instance for the struct.

header.h

struct common
{
    // ...
};   

.c

#include "header.h"
struct common C ;