7.2/getch.c


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#include <stdio.h>
#include <stdlib.h>
#include <error.h>
#include <errno.h>
#include "getch.h"

#define MAXBUFF 100

int gtop;
char buff[MAXBUFF];

char getch(void)
{
	return (gtop > 0) ? buff[--gtop] : getchar();
}

void ungetch(char c)
{
	if (gtop < MAXBUFF)
		buff[gtop++] = c;
	else
	 	error(EXIT_FAILURE, ENOBUFS, "getch");
}