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
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
#include <stdio.h>
#include <string.h>
#include <ctype.h>
/* The C Programming Language: 2nd Edition
*
* Exercise 6-1: Our version of `getword` does not properly handle underscores,
* string constants, comments, or preprocessor control lines. Write a better
* version.
*
* Notes: Preprocessor lines and one-line comments should be treated the same by
* ignoring everything after the beginning. Underscores need to be treated like
* part of the word, otherwise identifiers such as 'if_else' will get added to
* the list. Anything inside quotes and multi-line comments needs to be ignored,
* with a state variable to help us figure out what's going on.
*/
#define MAXWORD 100
#define BUFSIZE 1000
struct key {
char *word;
int count;
} keytab[] = {
"auto", 0,
"break", 0,
"case", 0,
"char", 0,
"const", 0,
"continue", 0,
"default", 0,
"else", 0,
"enum", 0,
"for", 0,
"if", 0,
"int", 0,
"long", 0,
"return", 0,
"short", 0,
"signed", 0,
"static", 0,
"struct", 0,
"switch", 0,
"typedef", 0,
"unsigned", 0,
"void", 0,
"volatile", 0,
"while", 0
};
#define NKEYS (sizeof keytab / sizeof(struct key))
char buf[BUFSIZE];
int bufp = 0;
enum states {
NORMAL,
INQUOTE,
INCOMMENT
};
int state = NORMAL;
int getch(void);
void ungetch(int);
int getword(char *, int);
int binsearch(char *, struct key *, int);
int main() {
int n;
char word[MAXWORD];
while (getword(word, MAXWORD) != EOF) {
if (isalpha(word[0])) {
if ((n = binsearch(word, keytab, NKEYS)) >= 0) {
keytab[n].count++;
}
}
}
for (n = 0; n < NKEYS; n++) {
if (keytab[n].count > 0) {
printf("%4d %s\n", keytab[n].count, keytab[n].word);
}
}
return 0;
}
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;
}
}
int binsearch(char *word, struct key tab[], int n) {
int cond;
int low, high, mid;
low = 0;
high = n - 1;
while (low <= high) {
mid = (low + high) / 2;
if ((cond = strcmp(word, tab[mid].word)) < 0) {
high = mid - 1;
} else if (cond > 0) {
low = mid + 1;
} else {
return mid;
}
}
return -1;
}
int getword(char *word, int lim) {
int c;
char *w = word;
while (isspace(c = getch())) {
}
if (c != EOF && c != '#' && c != '"' && c != '/' && c != '*') {
*w++ = c;
}
if (c == '*' && state == INCOMMENT) {
if ((c = getch()) == '/') {
state == NORMAL;
return '/';
}
}
/* Ignore comments */
if (c == '/') {
c = getch();
if (c == '/') {
while ((c = getch()) != EOF && c != '\n') {
}
return '*';
}
if (c == '*') {
state = INCOMMENT;
return '*';
}
}
/* Handle quotes */
if (c == '"') {
state = INQUOTE;
}
if (state == INQUOTE) {
while ((c = getch()) != '"' && c != EOF) {
}
state = NORMAL;
}
/* Ignore preprocessor lines */
if (c == '#') {
while ((c = getch()) != '\n' && c != EOF) {
}
}
/* Add exceptions for underscores */
if (!isalpha(c) && c != '_') {
*w = '\0';
return c;
}
for (; --lim > 0; w++) {
if (!isalnum(*w = getch()) && *w != '_') {
ungetch(*w);
break;
}
}
*w = '\0';
return word[0];
}
|
