To get the size of a member of a struct

To get the size of a member of a struct

[Eus]

Hi Ho!

Is `sizeof(((struct person *) 0)->name)' the proper way to retrieve the size of a
member of a struct without declaring a variable of that struct as demonstrated in
the program below? It is because I cannot do `sizeof(person->name)' or
`sizeof((struct person).name)'. Or, is there any other way to do so?

struct person
{
        int id;
        char name [50];
        double salary;
};

int main (int argc, char **argv, char **envp)
{
        printf ("sizeof(name) = %zd\n", sizeof(((struct person *) 0)->name));

        exit (EXIT_SUCCESS);
}

Thank you very much.

Best regards,
Eus


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Re: To get the size of a member of a struct

[Jim Wilson]

Eus wrote:
> Is `sizeof(((struct person *) 0)->name)' the proper way to retrieve the size of a
> member of a struct without declaring a variable of that struct as demonstrated in
> the program below?

It should work, but may not be the best solution.

Another solution is to define a type you can query, e.g. 

typedef char name_t[50];
and then use this in the struct definition and in the sizeof call.

Jim

Re: To get the size of a member of a struct

[Eus]

Hi Ho!

--- Jim Wilson <wilson@tuliptree.org> wrote:
> 
> It should work, but may not be the best solution.
> 
> Another solution is to define a type you can query, e.g. 
> 
> typedef char name_t[50];
> and then use this in the struct definition and in the sizeof call.

I think this is good. But, not everyone likes to use typedef, for example, Linus
Torvalds as he mentioned not to use typedef in the Linux kernel coding guideline
:)

> Jim

Best regards,
Eus


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