2005-08-26 04:48:05 +00:00
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/* wf1 - print word frequencies; uses structures */
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struct node {
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int count; /* frequency count */
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struct node *left; /* left subtree */
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struct node *right; /* right subtree */
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char *word; /* word itself */
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} words[2000];
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int next; /* index of next free entry in words */
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struct node *lookup();
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main()
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{
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struct node *root;
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char word[20];
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root = 0;
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next = 0;
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while (getword(word))
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lookup(word, &root)->count++;
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tprint(root);
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return 0;
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}
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/* err - print error message s and die */
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err(s)
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char *s;
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{
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printf("? %s\n", s);
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exit(1);
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}
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/* getword - get next input word into buf, return 0 on EOF */
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int getword(buf)
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char *buf;
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{
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char *s;
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int c;
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while ((c = getchar()) != -1 && isletter(c) == 0)
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;
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for (s = buf; c = isletter(c); c = getchar())
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*s++ = c;
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*s = 0;
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if (s > buf)
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return (1);
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return (0);
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}
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/* isletter - return folded version of c if it is a letter, 0 otherwise */
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int isletter(c)
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int c;
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{
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if (c >= 'A' && c <= 'Z')
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c += 'a' - 'A';
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if (c >= 'a' && c <= 'z')
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return (c);
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return (0);
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}
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/* lookup - lookup word in tree; install if necessary */
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struct node *lookup(word, p)
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char *word;
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struct node **p;
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{
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int cond;
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char *malloc();
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if (*p) {
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cond = strcmp(word, (*p)->word);
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if (cond < 0)
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return lookup(word, &(*p)->left);
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else if (cond > 0)
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return lookup(word, &(*p)->right);
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else
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return *p;
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}
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if (next >= 2000)
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err("out of node storage");
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words[next].count = 0;
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words[next].left = words[next].right = 0;
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words[next].word = malloc(strlen(word) + 1);
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if (words[next].word == 0)
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err("out of word storage");
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strcpy(words[next].word, word);
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return *p = &words[next++];
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}
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/* tprint - print tree */
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tprint(tree)
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struct node *tree;
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{
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if (tree) {
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tprint(tree->left);
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printf("%d\t%s\n", tree->count, tree->word);
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tprint(tree->right);
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}
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}
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/* strcmp - compare s1 and s2, return <0, 0, or >0 */
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int strcmp(s1, s2)
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char *s1, *s2;
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{
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while (*s1 == *s2) {
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if (*s1++ == 0)
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return 0;
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++s2;
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}
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if (*s1 == 0)
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return -1;
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else if (*s2 == 0)
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return 1;
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return *s1 - *s2;
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}
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