Question

Here I have a pointer to the first element and int to hold the number of elements. How do I add in malloc and calloc for memory allocation?

struct vector_new           
  {
  char *start;
  int count;
  }

Answer 1

You are looking for a “dynamic array” implementation.

You keep track of both how many objects are currently in the array and how much space is allocated for it. When you need more space you call realloc and ask for current_size * factor where factor is greater than one. Typical values for factor are between 1.4 and 2.

It can be shown that the amortized cost of appending n items to the array is O(n).

Note that this is not efficient if you want to insert stuff into the middle. That’s a different critter.