Equality of structure using pragma pack in C

Question

The reason behind the fact that the structures can't be checked for equality in C is the presence of slack bytes,which makes the comparison impossible.

But if I use #pragma pack(1) which removes the slack bytes then the comparison should be done smoothly,but it still gives error on being compared.

Example Code

#include<stdio.h>
#pragma pack(1)
struct person
{
    int uid;
    char nameStart;
};
struct personDupe
{
    int uid;
    char nameStart;
};
int main()
{
    struct person var;
    struct personDupe varDupe;
    printf("\nSize of person : %3d\n",sizeof(var));
    printf("\nSize of personDupe : %3d\n",sizeof(varDupe));

    var.uid = 12;
    var.nameStart = 'a';

    varDupe.uid = 12;
    varDupe.nameStart = 'a';

    if(var == varDupe)    //Error is introduced
        printf("\nStructures are equal\n");
    return 0;
}

Answer 1

You can also tell the compiler how you detect that two values are the same

bool same_person(struct person* p, struct personDupe* dupe)
{ return p->uid == dupe->uid && p->nameStart == dupe->nameStart; }

And then you can do

if(same_person(&var, &varDupe))
    printf("\nStructures are equal\n");