A dynamic stack data structure made in C

dynamic-stack.c

#include <stdlib.h>
#include <stdio.h>
#define DEFAULT_SIZE 16

int no_of_words = 0;            //Number of elements in array
int array_size = DEFAULT_SIZE;
int *stack;                     //Stack pointer

void init_stack() {
  stack = malloc(sizeof(uint32_t) * DEFAULT_SIZE);
}

void destroy_stack() {
  free(stack)
}

//Allocate a new chunk of memory with half the size.
//Copy the old stack to the new memory and free up
//the old stack.
void shrink_capacity() {
  array_size /= 2;
  int *new_stack = malloc(sizeof(uint32_t) * array_size);
  int i;
  for (i = 0; i < no_of_words; i++) {
    new_stack[i] = stack[i];
  }
  free(stack);
  stack = new_stack;
}

void double_capacity() {
  array_size *= 2;
  stack = realloc(stack, sizeof(uint32_t) * array_size);
}


/*************************************************************
  * Stack operations
*************************************************************/

//Check if the number of elements is less than half the array size
//and shrink the capacity if true.
//Remove and return the element on top of the stack.
int pop() {
  if (no_of_words < array_size / 2 && no_of_words > DEFAULT_SIZE) {
    shrink_capacity();
  }
  int removed_word = stack[no_of_words - 1];
  no_of_words -= 1;
  return removed_word;
}

//Check if malloc and realloc returned a pointer.
//The capacity is doubled if the number of elements
//equals the array size.
//Add an element to the stack.
void push(int word){
  if(stack == NULL) {
    printf("Something went wrong, failed to allocate memory\n");
    exit(1);
  }
  if(no_of_words == array_size) {
    double_capacity();
  }
  stack[no_of_words] = word;
  no_of_words += 1;
}

//Returns the top element
int top() {
  return (int) stack[no_of_words - 1];
}

int size() {
  return no_of_words;
}