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/* wf1 - print word frequencies; uses structures */
struct node {
int count; /* frequency count */
struct node *left; /* left subtree */
struct node *right; /* right subtree */
char *word; /* word itself */
} words[2000];
int next; /* index of next free entry in words */
struct node *lookup();
main()
{
struct node *root;
char word[20];
root = 0;
next = 0;
while (getword(word))
lookup(word, &root)->count++;
tprint(root);
return 0;
}
/* err - print error message s and die */
err(s)
char *s;
{
printf("? %s\n", s);
exit(1);
}
/* getword - get next input word into buf, return 0 on EOF */
int getword(buf)
char *buf;
{
char *s;
int c;
while ((c = getchar()) != -1 && isletter(c) == 0)
;
for (s = buf; c = isletter(c); c = getchar())
*s++ = c;
*s = 0;
if (s > buf)
return (1);
return (0);
}
/* isletter - return folded version of c if it is a letter, 0 otherwise */
int isletter(c)
int c;
{
if (c >= 'A' && c <= 'Z')
c += 'a' - 'A';
if (c >= 'a' && c <= 'z')
return (c);
return (0);
}
/* lookup - lookup word in tree; install if necessary */
struct node *lookup(word, p)
char *word;
struct node **p;
{
int cond;
char *malloc();
if (*p) {
cond = strcmp(word, (*p)->word);
if (cond < 0)
return lookup(word, &(*p)->left);
else if (cond > 0)
return lookup(word, &(*p)->right);
else
return *p;
}
if (next >= 2000)
err("out of node storage");
words[next].count = 0;
words[next].left = words[next].right = 0;
words[next].word = malloc(strlen(word) + 1);
if (words[next].word == 0)
err("out of word storage");
strcpy(words[next].word, word);
return *p = &words[next++];
}
/* tprint - print tree */
tprint(tree)
struct node *tree;
{
if (tree) {
tprint(tree->left);
printf("%d\t%s\n", tree->count, tree->word);
tprint(tree->right);
}
}
/* strcmp - compare s1 and s2, return <0, 0, or >0 */
int strcmp(s1, s2)
char *s1, *s2;
{
while (*s1 == *s2) {
if (*s1++ == 0)
return 0;
++s2;
}
if (*s1 == 0)
return -1;
else if (*s2 == 0)
return 1;
return *s1 - *s2;
}
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