Nested struct variable initialization

Question

How can I initialize this nested struct in C?

typedef struct _s0 {
   int size;
   double * elems;
}StructInner ;

typedef struct _s1 {
   StructInner a, b, c, d, e;
   long f;
   char[16] s;
}StructOuter;  StructOuter myvar = {/* what ? */ };

Answer 1

double a[] = { 1.0, 2.0 };
double b[] = { 1.0, 2.0, 3.0 };
StructOuter myvar = { { 2, a }, { 3, b }, { 2, a }, { 3, b }, { 2, a }, 1, "a" };

It seems a and b cannot be initialized in-place in plain C

Answer 2

There's a similar post here on SO for C++.

Answer 3

To initialize everything to 0 (of the right kind)

StructOuter myvar = {0};

To initialize the members to a specific value

StructOuter myvar = {{0, NULL}, {0, NULL}, {0, NULL},
                     {0, NULL}, {0, NULL}, 42.0, "foo"};
/* that's {a, b, c, d, e, f, s} */
/* where each of a, b, c, d, e is {size, elems} */

---

Edit

If you have a C99 compiler, you can also use "designated initializers", as in:

StructOuter myvar = {.c = {1000, NULL}, .f = 42.0, .s = "foo"};
/* c, f, and s initialized to specific values */
/* a, b, d, and e will be initialized to 0 (of the right kind) */