1 /*
2  * Exercise 4-8. Suppose that there will never be more than one character of
3  * pushback. Modify getch and ungetch accordingly.
4  *
5  */
6 
7 #include <stdio.h>
8 #include <string.h>
9 
10 #define MAXLENGTH 800
11 
12 int getch(void);
13 void ungetch(int c);
14 
15 #define BUFSIZE 100
16 
17 char buf = EOF; /* buffer for ungetch */
18 
19 /* get a (possibly pushed back) character, \0 if no character */
20 int getch(void) {
21 	char c = bufp;
22 	bufp = EOF;
23 	return c;
24 }
25 
26 /* push character back on input */
27 void ungetch(int c) {
28 	if (bufp == EOF)
29 		bufp = c;
30 	else
31 		printf("ungetch: too many characters\n");
32 }