//arrayStack.c
//John T. Rine
//October 28, 2011

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

struct Stack 
{
  char *array;
  int top;
  int size;
};

typedef struct Stack stack;

int cntChars(char *);
void createStack(stack *, int);
void push(stack *, char);
char pop(stack *);
int isEmpty(stack *);
int isFull(stack *);

int main(int argc, char **argv)
{
	int i;
	int count;
	stack newStack;
	char stringArray[200];

	printf("Enter a string: ");
	gets(stringArray); 
	count = cntChars(stringArray); 
	createStack(&newStack, count); 
	if(isEmpty(&newStack)) printf("Stack is empty\n");
	else printf("Stack is not empty\n");
	for(i = 0; i < count; i++)
	{
		push(&newStack,stringArray[i]);
                printf("The character going into tos is: %c\n", newStack.array[i]);
	}
        if(isEmpty(&newStack)) printf("Stack is empty\n");
        else printf("Stack is not empty\n");
	for(i = 0; i < count; i++) printf("The character in tos is: %c\n", pop(&newStack));
        for(i = 0; i < count; i++)
        {
                push(&newStack,stringArray[i]);
                printf("The character going into tos is: %c\n", newStack.array[i]);
        }
	push(&newStack,'H');

	return 0;
}

int cntChars(char *inputString)
{
	// returned value "count" does not include '\0'
	int count = 0;
	while(*(inputString + count) != '\0') ++count;
	return(count);
}

void createStack(stack *stackVar, int size)
{
	char *array;

	array = (char *)malloc(sizeof(char) * size);

  	if (array == NULL)
	{
    		fprintf(stderr, "Not enough memory to create the stack.\n");
    		exit(1);
  	}

	stackVar->array = array;
  	stackVar->size = size;
  	stackVar->top = -1;

}

int isEmpty(stack *stackVar)
{
  return stackVar->top < 0;
}

int isFull(stack *stackVar)
{
  return stackVar->top >= stackVar->size - 1;
}

void push(stack *stackVar, char  element)
{
	if (isFull(stackVar))
	{
		fprintf(stderr, "Can't push on the stack is full\n");
		exit(1);
	}
	stackVar->array[++stackVar->top] = element;
}


char pop(stack *stackVar)
{
	if (isEmpty(stackVar))
	{
		fprintf(stderr, "Can't pop from stack; stack is empty\n");
		exit(1);
	}
	return stackVar->array[stackVar->top--];
}