Interacting with C arrays without knowing the size

So when we want to use an array without knowing the size then the common procedure is to start small and then keep doubling the size and reallocating it as we go along right?

And then I assume once we are done we will want to realloc once more to free up the excess memory that was malloced and we did not use?

#include <stdio.h>
#include <stdlib.h>

int main()
{
    // unknown = an unknown amount of work we need to do
    int unknown = 1234;

    // size = the current allocated memory
    int size = 10;

    // counter = the final size of the array
    int counter = 0;

    // first we allocate a small amount for our array
    int *array = (int *) malloc(size * sizeof(int));

    // and then start working
    for(int i = 0; i < unknown; i++)
    {
        // work
        array[i] = i; counter++;

        // check the size of the array to see if we need to realloc
        if (counter == size)
        {
            size *= 2;
            array = (int *) realloc(array, sizeof(size));
        }
    }

    // when all of the work is done we then shorten it to the exact size
    array = (int *) realloc(array, sizeof(counter));

    printf("%d", counter);
}

Question 1: Is this the most performant way of tackling this problem?

Question 2: Since we need to keep track of the size of the array do most people create a struct for this?

typedef struct list
{
    int size;
    int *array;
} list;

You need to sign in to view this answers