Thread: Using Offset in C

Hi All

I am trying to understand offset in C and create it to print out the members reside on memory location using offset.

I have written following code:

Code:

#include<stdio.h>
#include<conio.h>

typedef struct
{
	char name[10];
	int age;
	char address[100];
} record;

int main()
{
   record rec,*ptr,p;
   int offset = 0;
   memset(&rec,0x00,sizeof(rec));
   memcpy(rec.name,"NICKMAN",7);
   memcpy(rec.address,"13 ALMOND STREET",20);
   rec.age = 17;
   ptr = &rec;

   offset = (char *)rec.name - (char *)ptr; 
   
   return 1;


}

Is this the correct way of creating offset?

Also, how can I print the members using it.

Can any body me further from here?

Thanks
Nickman

Use the offsetof macro:

Code:

#include <stddef.h>
...
printf("offset of address is %zu\n", offsetof(record, address));

return 0;

Remember to #include <stddef.h> so you can use the macro. The "%zu" is for printing size_t types, which is what offsetof returns. Returning 1 from main usually designates some sort of error in your program. You should return 0 or EXIT_SUCCESS.