# allocation growing API

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

Define your array with:

- a pointer (`item`) that points at the array, initialized to `NULL` (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 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 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`.