C言語でスタック

stack.c

#include <stdio.h>

#define STACKSIZE 3000

struct Stack {
  int buffer[STACKSIZE];
  int length;
};

int push(struct Stack *stack, int data) {
  stack->buffer[stack->length] = data;
  stack->length++;

  return 0;
};

int pop(struct Stack *stack) {
  stack->length--;

  return stack->buffer[stack->length];
};

int main(int argc, char const* argv[])
{
  struct Stack marisa;
  marisa.length = 0;

  push(&marisa, 1);
  push(&marisa, 1);
  push(&marisa, 4);
  push(&marisa, 5);
  push(&marisa, 1);
  push(&marisa, 4);

  printf("%d\n",pop(&marisa));
  printf("%d\n",pop(&marisa));
  printf("%d\n",pop(&marisa));
  printf("%d\n",pop(&marisa));
  printf("%d\n",pop(&marisa));
  printf("%d\n",pop(&marisa));

  return 0;
}