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#include <stdio.h>
#include <stdlib.h>
#include "stack_array.h"
#define EMPTY_TOS (-1)
#define MIN_STACK_SIZE (5)
struct stack_record
{
int capacity;
int top_of_stack;
elem *array;
};
stack create_stack(int max_elements)
{
stack s;
if(max_elements < MIN_STACK_SIZE)
printf("size too small.\n");
s = malloc(sizeof(struct stack_record));
if(s == NULL)
printf("out of space");
s->array = malloc(sizeof(elem) * max_elements);
if(s->array == NULL)
printf("out of space");
s->capacity = max_elements;
make_empty(s);
return s;
}
void dispose_stack(stack s)
{
if(s != NULL) {
free(s->array);
free(s);
}
}
int is_empty(stack s)
{
return s->top_of_stack == EMPTY_TOS;
}
void make_empty(stack s)
{
s->top_of_stack = EMPTY_TOS;
}
void push(elem x, stack s)
{
if(s->top_of_stack >= s->capacity)
printf("full stack");
else
s->array[++s->top_of_stack] = x;
}
elem top(stack s)
{
if(!is_empty(s))
return s->array[s->top_of_stack];
printf("empty stack");
return 0;
}
void pop(stack s)
{
if(!is_empty(s))
s->top_of_stack--;
printf("empty stack");
}
elem top_and_pop(stack s)
{
if(!is_empty(s))
/* take care of this, before return, s->top_of_stack is already dec. */
return s->array[s->top_of_stack--];
printf("empty stack");
return 0;
}
int main()
{
stack s = create_stack(100);
push(1, s);
push(2, s);
push(3, s);
printf("%d\n", top_and_pop(s));
printf("%d\n", top_and_pop(s));
return 0;
}
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