1 files changed, 101 insertions, 0 deletions
diff --git a/lcc/tst/wf1.c b/lcc/tst/wf1.c
new file mode 100755
index 0000000..a95b4ec
--- /dev/null
+++ b/lcc/tst/wf1.c
@@ -0,0 +1,101 @@
+/* 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) {
+	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;
+}