[완료]TCPL 에 나오는 예문중 하나인데요.

1 #include
2 #include
3 #include
4
5 #define MAXWORD 100
6 #define BUFSIZE 100
7 #define NKEYS (sizeof keytab/ sizeof(struct key))
8
9 struct key{
10 char *word;
11 int count;
12 }keytab[] = {
13 "auto",0,
14 "break",0,
15 "case",0,
16 "char",0,
17 "const",0,
18 "continue",0,
19 "default",0,
20 "unsigned",0,
21 "void",0,
22 "volatile",0,
23 "while",0,
24 };
25
26
27 char buf[BUFSIZE]; /*buffer for ungetch*/
28 int bufp = 0; /* next free position in buf */
29
30 int getword(char *,int);
31 int binsearch(char *, struct key *,int);
32
33 // count C keywords
34 main()
35 {
36 int n;
37 char word[MAXWORD];
38
39 while(getword(word,MAXWORD)!=EOF)
40 if(isalpha(word[0]))
41 if((n=binsearch(word,keytab,NKEYS)) >= 0)
42 keytab[n].count++;
43 for(n=0;n 44 if(keytab[n].count>0)
45 printf("%4d %s\n", keytab[n].count, keytab[n].word);
46 return 0;
47 }
48
49 // binsearch: find word in tab[0]...tab[n-1]
50 int binsearch(char* word, struct key tab[],int n)
51 {
52 int cond;
53 int low,high,mid;
54
55 low = 0 ;
56 high = n-1;
57 while(low<=high){
58 mid = (low+high)/2;
59 if((cond = strcmp(word,tab[mid].word))<0)
60 high = mid - 1;
61 else if(cond > 0)
62 low = mid +1;
63 else return mid;
64 }
65 return -1;
66 }
67
68 // getword: get next word or character from input
69 int getword(char *word, int lim)
70 {
71 int c,getch(void);
72 void ungetch(int);
73 char *w = word;
74
75 while(isspace(c=getch()))
76 ;
77 if(c!=EOF)
78 *w++ = c;
79 if(!isalpha(c)){
80 *w = '\0';
81 return c;
82 }
83
84 for(;--lim>0;w++)
85 if(!isalnum(*w = getch())){
86 ungetch(*w);
87 break;
88 }
89 *w = '\0';
90 return word[0];
91 }
92
93 int getch(void) /* get a (possibly pushed back) character */
94 {
95 return (bufp>0)?buf[--bufp]:getchar();
96 }
97
98 void ungetch(int c) /* push character back on input */
99 {
100 if(bufp>=BUFSIZE)
101 printf("ungetch : too many characters\n");
102 else
103 buf[bufp++] = c;
104 }

이건 section 6.3 에나오는 keyword 찾는 예제인데요. 궁금한것은..getword()함수 인데요.
77번 라인에if(c!=EOF)*w++ = c; 이 문장은 왜 필요한지 궁금해서요.
후에 for문에서 모든 입력을 다 받아서 word를 완성시키는데. 왜 앞부분에서 첫번째 문자를 따로 다루는지 모르겠네요.