Stack .h/.c
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stack.h
-------
#define SIZE 7
#define TYPE char

typedef enum{FALSE,TRUE} bul;

typedef struct stack
{
		TYPE ar[SIZE];
		int top;
}stack;

void stack_init(stack *s);
bul stack_empty(stack s);
bul stack_full(stack s);
bul push(stack *s,TYPE item);
bul pop(stack *s,TYPE *item);

stack.c
-------
#include "stack.h"

void stack_init(stack *s)
{
	s->top = -1;
}
bul stack_empty(stack s)
{
	return (s.top == -1)?TRUE:FALSE;
}
bul stack_full(stack s)
{
	return (s.top == SIZE-1)?TRUE:FALSE;
}
bul push(stack *s, TYPE item)
{
	if(!stack_full(*s))
	{
		s->ar[++(s->top)] = item;
		return TRUE;
	}
	return FALSE;
}
bul pop (stack *s,TYPE *item)
{
	if(!stack_empty(*s))
	{	
		*item = s->ar[s->top--];
		return TRUE;
	}
	return FALSE;
}	
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//MAIN
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#include <stdio.h>
#include "stack.h"

void main()
{
	stack s1;
	stack s2;
	int i;
	int flag=1;
	TYPE ch,ch1;
	
	stack_init(&s1);
	stack_init(&s2);
	
	
	while(!stack_full(s1))
	{
		printf("Enter a char\n");
		scanf("%c",&ch);
		push(&s1,ch);
	}
	pop(&s1,&ch);
	while(ch!='C'&&!stack_empty(s1))
	{
		push(&s2,ch);
		pop(&s1,&ch);	
	}
	pop(&s1,&ch);
	
	if(ch == 'C')
		while(!stack_empty(s1)&&!stack_empty(s2)&&flag)
		{
			pop(&s1,&ch);
			pop(&s2,&ch1);
			
			(ch != ch1)?(flag=0):0;
		}
	else
		printf("The string is invalid");

	(flag)?(printf("The string is good")):(printf("The string is invalid"));
		
}