Question

I’m having a bit of issue with pointers and structures in c.

struct foo{
char a[15];
}

void asn_foo(struct foo *pa){
    (*pa).a = "123";
}

main()
{
    struct foo foo1[2], *pf;
    pf = &(foo1[0]);
    asn_foo(pf);
}

I’m trying to assign a new value by:

(*pa).a = "123";

but I have the error “Incompatible types in assignment” on this line.
What am I doing wrong?

Answer 1

You can’t assign new values to an array using the assignment operator, you have to copy the contents of the string "123" into your array. Use strcpy to do so:

strcpy(pa->a, "123");

Another trick is also wrapping your array in a struct (as you’ve done here), and assigning one struct to another in order to assign new values to your array.

You can do:

struct foo f1 = { "abc" };
struct foo f2 = { "123" };
f1 = f2;

f1.a will now hold "123".

Also, main should return an int.