Question

#include <stdio.h>
#include <string.h>

struct s
{
    int data;
} fun()
{
    static struct s ss; 
    ss.data = 20;
    return ss;
}

int main()
{
    struct s ss;
    memcpy(&ss, &(fun()), sizeof(struct s));

    printf("\n Data: :%d", ss.data);

    return 0;
}

In the above program, Im trying to define a struct where the return type is mentioned. struct s is defined successfully.

Is this a valid usage? I never seen real scenario like this.

How to make this program to work??

I’m getting this compiler error:

asd.c: In function ‘main’:
asd.c:21:15: error: lvalue required as unary ‘&’ operand

Answer 1

Everything apart from your memcpy line is correct (albeit a bit hard to read), and the compiler error tells you what’s wrong: You can’t take the address of a “temporary” (i.e. of the result of a function call ex­pres­sion).

You could and should however just write the much more natural way:

struct s ss = fun();