A good C equivalent of STL vector?

Question

I\'ve noticed that at several places in our code base we use dynamically expanding arrays, i.e. a base array coupled with an element counter and a \"max elements\" value.

Answer 1

I'm using the following macro implementation without problems so far. It isn't a complete implementation but grows the array automatically :

#define DECLARE_DYN_ARRAY(T) \
    typedef struct \
    { \
        T *buf; \
        size_t n; \
        size_t reserved; \
    } T ## Array;

#define DYN_ARRAY(T) T ## Array

#define DYN_ADD(array, value, errorLabel) DYN_ADD_REALLOC(array, value, errorLabel, realloc)

#define DYN_ADD_REALLOC(array, value, errorLabel, realloc) \
    { \
        if ((array).n >= (array).reserved) \
        { \
            if (!(array).reserved) (array).reserved = 10; \
            (array).reserved *= 2; \
            void *ptr = realloc((array).buf, sizeof(*(array).buf)*(array).reserved); \
            if (!ptr) goto errorLabel; \
            (array).buf = ptr; \
        } \
        (array).buf[(array).n++] = value; \
    }

To use you first write: DECLARE_DYN_ARRAY(YourType)

To declare variables you write DYN_ARRAY(YourType) array = {0}.

You add elements with DYN_ADD(array, element, errorLabel).

You access elements with array.buf[i].

You get the number of elements with array.n.

When done you free it with free(array.buf) (or whatever function you used to allocate it.)