Question

Hi i want to make a function which calculate the size of structure without padding bytes.

Example :

struct test{
    int   x;
    char  y;
    int   z;
};

If i calculate the size of above structure i must get 9 byte (i.e. without padding bytes)

And consider the case where i might not know the variable present in struct.

Example :

struct test{
    int   x;
    ....
    ....
    ....
    int   z;
};

so if i calculate the size it should give correct size.

Is it possible do write such function?I tried reading on structure’s but i dint find any solution.I saw there is some compiler option are present from that i can get but i dont want any in build compiler option.

Answer 1

No, C doesn’t have enough introspection to make this possible. At run-time, there is no information left that the program can use to “know” which fields are in a structure, or what their types are.