Struct pointer compatibility

Question

Suppose we have two structs:

typedef struct Struct1
{
    short a_short;
    int id;
} Struct1;

typedef struct Struct2
{
    short a_short;
    int id;
             


        

Answer 1

Yes, it is ok to do that!

A sample program is as follows.

#include 

typedef struct Struct1
{
    short a_short;
    int id; 
} Struct1;

typedef struct Struct2
{
    short a_short;
    int id; 
    short another_short;
} Struct2;

int main(void) 
{

    Struct2 s2 = {1, 2, 3}; 
    Struct1 *ptr = &s2;
    void *vp = &s2;
    Struct1 *s1ptr = (Struct1 *)vp;

    printf("%d, %d \n", ptr->a_short, ptr->id);
    printf("%d, %d \n", s1ptr->a_short, s1ptr->id);

    return 0;
}