5.19/getch.c


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#include <stdlib.h>
#include <stdio.h>
#include "err.h"
#include "getch.h"

#define MAXBUFF	100

char buff[MAXBUFF];
static size_t top;

void ungetch(char c)
{
	if (top < MAXBUFF)
		buff[top++] = c;
	else
		err("buff: stack overflow");
}

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