Dynamically growing an array using realloc() is error prone and boring.
Define your array with:
- 
a pointer ( item) that points at the array, initialized toNULL(although please name the variable based on its contents, not on its type);
- 
an integer variable ( alloc) that keeps track of how big the current allocation is, initialized to0;
- 
another integer variable ( nr) to keep track of how many elements the array currently has, initialized to0.
Then before adding n`th element to the item, call `ALLOC_GROW(item, n,
alloc).  This ensures that the array can hold at least n elements by
calling realloc(3) and adjusting alloc variable.
sometype *item;
size_t nr;
size_t alloc
for (i = 0; i < nr; i++)
        if (we like item[i] already)
                return;
/* we did not like any existing one, so add one */
ALLOC_GROW(item, nr + 1, alloc);
item[nr++] = value you like;You are responsible for updating the nr variable.
If you need to specify the number of elements to allocate explicitly
then use the macro REALLOC_ARRAY(item, alloc) instead of ALLOC_GROW.