blob: 8d53ba61e18502f9d1b33dc20e1e5ecd3d63b80a (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
#include <stdio.h>
#include <ctype.h>
/* The C Programming Language: 2nd Edition
*
* Exercise 5-1: As written, getint treats a + or - not followed by a digit as
* a valid representation of zero. Fix it to push such a character back on the
* input.
*/
#define BUFSIZE 100
int getch(void);
void ungetch(int);
int getint(int *);
char buf[BUFSIZE];
int bufp = 0;
int main() {
int foo;
int *bar = &foo;
while (getint(bar) > 0) {
printf("%d\n", foo);
}
return 0;
}
int getint(int *pn) {
int c, sign;
while (isspace(c = getch())) {
}
if (!isdigit(c) && c != EOF && c != '+' && c != '-') {
ungetch(c);
return 0;
}
sign = (c == '-') ? -1 : 1;
if (c == '+' || c == '-') {
c = getch();
}
if (!isdigit(c)) {
return 0;
}
for (*pn = 0; isdigit(c); c = getch()) {
*pn = 10 * *pn + (c - '0');
}
*pn *= sign;
if (c != EOF) {
ungetch(c);
}
return c;
}
int getch(void) {
return (bufp > 0) ? buf[--bufp] : getchar();
}
void ungetch(int c) {
if (bufp >= BUFSIZE) {
printf("ungetch: Too many characters.\n");
} else {
buf[bufp++] = c;
}
}
|
