Dynamically growing an array using realloc() is error prone and boring.

Define your array with:

  • a pointer (ary) that points at the array, initialized to NULL;

  • an integer variable (alloc) that keeps track of how big the current allocation is, initialized to 0;

  • another integer variable (nr) to keep track of how many elements the array currently has, initialized to 0.

Then before adding n`th element to the array, call `ALLOC_GROW(ary, n, alloc). This ensures that the array can hold at least n elements by calling realloc(3) and adjusting alloc variable.

sometype *ary;
size_t nr;
size_t alloc

for (i = 0; i < nr; i++)
        if (we like ary[i] already)
                return;

/* we did not like any existing one, so add one */
ALLOC_GROW(ary, nr + 1, alloc);
ary[nr++] = value you like;

You are responsible for updating the nr variable.