CS 245 Homework 1

Due Date

4:00 pm Friday September 18

Assignment Name

stack

File Names

stack.c stack.h

Make the following changes to the stack data structure below (both stack.c and stack.h).

1. When a item is pushed and the stack is full, resize it by using realloc to double the size of the array.
2. Change the type of items stored in the stack from int to string (char *).
3. When a string is pushed, push the actual argument (do not make a copy). It will be the responsiblity of the caller to copy a string before pushing if that is what's needed.

Turnin will compile my test program together with your stack implementation. Do not include a main program.

stack.h

// stack.c - An array implemention of the stack data structure.

#include <stdlib.h>
#include <assert.h>
#include "stack.h"

struct stack {
  int size;
  int *contents;
  int top;
};

stack *stack_new(int size) {
  stack *s = malloc(sizeof(struct stack));
  if (s == NULL) return NULL;
  s->size = size;
  s->contents = malloc(size * sizeof(int));
  if (s->contents == NULL) {
    free(s);
    return NULL;
  }
  s->top = -1;
  return s;
}

void stack_push(stack *s, int value) {
  assert(s->top < s->size - 1);
  s->contents[++(s->top)] = value;
}

int stack_pop(stack *s) {
  assert(s->top != -1);
  return s->contents[s->top--];
}

bool stack_isempty(stack *s) {
  return s->top == -1;
}

void stack_free(stack *s) {
  free(s->contents);
  free(s);
}

stack.h

// stack.c - An array implemention of the stack data structure.

#ifndef STACK_H
#define STACK_H

typedef struct stack stack;

stack *stack_new(int size);
void stack_push(stack *s, int value);
int stack_pop(stack *s);
bool stack_isempty(stack *s);
void stack_free(stack *s);

#endif