initialize array inside struct in C

Question

struct myStruct
{   
    short int myarr[1000];//want to initialize all elements to 0
}

How do I initialize the array?

I tried doing short int* myarr[1000]={0} inside the struct but it's wrong. How can I do this? I don't mind doing it in the implementation file. This struct is contained in a header file.

Answer 1

Use the universal initializer: {0}.

The universal initializer works for anything and initializes the elements to the proper 0 (NULL for pointers, 0 for ints, 0.0 for doubles, ...):

struct myStruct example1 = {0};
struct myStruct example2[42] = {0};
struct myStruct *example3 = {0};

---

Edit for dynamically allocated objects.

If you're allocating memory dynamically use calloc rather than malloc.

p = malloc(nelems * sizeof *p); /* uninitialized objects; p[2] is indeterminate */
q = calloc(nelems, sizeof *q);  /* initialized to zero; q[2] is all zeros */

With realloc (and possibly other situations) you need to memset.

Answer 2

If it is declared out of a function (not on the stack), the whole struct will be zeroed at compile time.

Otherwise, you can use memset after declaring it.