8 files changed, 217 insertions, 0 deletions
diff --git a/6.2/Makefile b/6.2/Makefile
new file mode 100644
index 0000000..d3991c3
--- /dev/null
+++ b/6.2/Makefile
@@ -0,0 +1,13 @@
+objects = main.o getch.o word.o tree.o
+CC = gcc
+CFLAGS = -Wvla -Wall -Wextra -Wstrict-prototypes -Wmissing-prototypes -fsanitize=address
+
+words : $(objects)
+	$(CC) $(CFLAGS) -o words $(objects)
+
+main.o : word.h tree.h
+word.o : getch.h
+
+.PHONY : clean
+clean :
+	rm words $(objects)
diff --git a/6.2/getch.c b/6.2/getch.c
new file mode 100644
index 0000000..2b86efe
--- /dev/null
+++ b/6.2/getch.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <error.h>
+#include <errno.h>
+#include "getch.h"
+
+#define MAXBUFF	100
+
+char buff[MAXBUFF];
+static size_t top;
+
+void ungetch(char c)
+{
+	if (top < MAXBUFF)
+		buff[top++] = c;
+	else
+		error(EXIT_FAILURE, ENOBUFS , "getch");
+}
+
+char getch(void)
+{
+	return (top > 0) ? buff[--top] : getchar();
+}
diff --git a/6.2/getch.h b/6.2/getch.h
new file mode 100644
index 0000000..cbfe8ad
--- /dev/null
+++ b/6.2/getch.h
@@ -0,0 +1,2 @@
+void ungetch(char c);
+char getch(void);
diff --git a/6.2/main.c b/6.2/main.c
new file mode 100644
index 0000000..57b562a
--- /dev/null
+++ b/6.2/main.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include "word.h"
+#include "tree.h"
+
+#define MAXWORD 100
+#define DEFLEN	6
+
+int main(int argc, char *argv[])
+{
+	struct tnode *root;
+	char word[MAXWORD];
+	int bar;
+
+	bar = (--argc && (**++argv == '-')) ? atoi(argv[0]+1) : DEFLEN;
+	root = NULL;
+	while (getword(word, MAXWORD) != EOF)
+		if ((isalpha(word[0]) || (word[0] == '#' && isalpha(word[1]))) &&
+			strlen(word) > (size_t) bar)
+			root = naddtree(root, word, bar, NO);
+
+	ntreeprint(root);
+	treefree(root);
+
+	return 0;
+}
diff --git a/6.2/tree.c b/6.2/tree.c
new file mode 100644
index 0000000..5e061a4
--- /dev/null
+++ b/6.2/tree.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "tree.h"
+
+struct tnode *naddtree(struct tnode *p, char *w, int bar, int prevmatch)
+{
+	int cond;
+
+	if (p == NULL) {
+		p = talloc();
+		p->word = sneed_strdup(w);
+		p->count = 1;
+		p->match = prevmatch;
+		p->left = p->right = NULL;
+	} else {
+		if ((!strncmp(p->word, w, bar) && strcmp(p->word, w)))
+			p->match = prevmatch = YES;
+
+		if ((cond = strcmp(w, p->word)) == 0) {
+			p->count++;
+		} else if (cond < 0) {
+			p->left = naddtree(p->left, w, bar, prevmatch);
+		} else if (cond > 0) {
+			p->right = naddtree(p->right, w, bar, prevmatch);
+		}
+	}
+
+	return p;
+}
+
+void ntreeprint(struct tnode *p)
+{
+	if (p != NULL) {
+		ntreeprint(p->left);
+		if (p->match)
+			printf("%4d %s\n", p->count, p->word);
+		ntreeprint(p->right);
+	}
+}
+
+void treefree(struct tnode *p) {
+	if (p != NULL) {
+		if (p->left != NULL)
+			treefree(p->left);
+		if (p->right != NULL)
+			treefree(p->right);
+		free(p->word);
+		free(p);
+	}
+}
+
+struct tnode *talloc(void)
+{
+	return (struct tnode *) malloc(sizeof(struct tnode));
+}
+
+char *sneed_strdup(char *s)
+{
+	char *p;
+
+	p = (char *) malloc(strlen(s) + 1);
+	if (p != NULL)
+		strcpy(p, s);
+
+	return p;
+}
diff --git a/6.2/tree.h b/6.2/tree.h
new file mode 100644
index 0000000..e976495
--- /dev/null
+++ b/6.2/tree.h
@@ -0,0 +1,20 @@
+#ifndef TREE_H
+
+struct tnode {
+	char *word;
+	int count;
+	int match;
+	struct tnode *left;
+	struct tnode *right;
+};
+
+enum { NO, YES };
+
+#define TREE_H
+#endif
+
+struct tnode *naddtree(struct tnode *p, char *w, int bar, int prevmatch);
+void ntreeprint(struct tnode *p);
+void treefree(struct tnode *p);
+struct tnode *talloc(void);
+char *sneed_strdup(char *s);
diff --git a/6.2/word.c b/6.2/word.c
new file mode 100644
index 0000000..1c5503a
--- /dev/null
+++ b/6.2/word.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <ctype.h>
+#include "getch.h"
+#include "word.h"
+
+char scomment(void);
+
+int getword(char *word, int lim)
+{
+	char *w = word;
+	
+	while (isblank(*w = getch()) || *w == '"' || *w == '/') {
+		if (*w == '"') {
+			while ((*w = getch()) != '"' && *w != EOF)
+				;
+			if (*w == EOF)
+				ungetch(*w);
+		} else if (*w == '/' && !scomment()) {
+			break;
+		}
+	}
+
+	if (isalpha(*w)) {
+		while ((isalnum(*w) || *w == '_') && --lim > 0)
+			*++w = getch();
+		ungetch(*w--);
+	} else if (*w == '#') {
+		--lim;
+		do {
+			*++w = getch();
+		} while (isalpha(*w) && --lim > 0);
+		ungetch(*w--);
+	}
+
+	*++w = '\0';
+	return word[0];
+}
+
+char scomment(void)
+{
+	char c;
+
+	switch (c = getch()) {
+	case '/' :
+		while ((c = getch()) != EOF && c != '\n')
+			;
+		if (c == EOF)
+			ungetch(c);
+
+		return '/';
+	case '*' :
+		while ((c = getch()) != EOF && !(c == '*' && (c = getch()) == '/'))
+			if (c == '*')
+				ungetch(c);
+		if (c == EOF)
+			ungetch(c);
+
+		return '*';
+	default:
+		ungetch(c);
+		return 0;
+	}
+}
diff --git a/6.2/word.h b/6.2/word.h
new file mode 100644
index 0000000..5714c50
--- /dev/null
+++ b/6.2/word.h
@@ -0,0 +1 @@
+int getword(char *word, int len);