K&R C Chapter 6 Exercise Solutions — Structures

Chapter 6: Structures introduces struct, typedef, and self-referential structures (linked lists, binary trees). The chapter builds a word-frequency counter using a binary tree, then extends it with a hash table. Exercise 6-3 adds a cross-reference listing; 6-6 implements a rudimentary #define processor using a hash table — the most complex exercise in this chapter.

These are worked solutions to all 6 exercises. Each solution compiles cleanly with gcc -ansi -Wall.

Book: The C Programming Language, 2nd Ed — Kernighan & Ritchie  |  All chapters index

Exercises

1. Exercise 6-1. Our version of getword does not properly handle underscores, string constants, comments, or preprocessor control lines. Write a better version.

   Solution to Exercise 6-1

2. Exercise 6-2. Write a program that reads a C program and prints in alphabetical order each group of variable names that are identical in the first 6 characters, but different somewhere thereafter. Don’t count words within strings and comments. Make 6 a parameter that can be set from the command line.

   Solution to Exercise 6-2

3. Exercise 6-3. Write a cross-referencer that prints a list of all words in a document, and for each word, a list of the line numbers on which it occurs. Remove noise words like “the”, “and”, and so on.

   Solution to Exercise 6-3

4. Exercise 6-4. Write a program that prints the distinct words in its input sorted into decreasing order of frequency of occurrence. Precede each word by its count.

   Solution to Exercise 6-4

5. Exercise 6-5. Write a function undef that will remove a name and definition from the table maintained by lookup and install.

   Solution to Exercise 6-5

6. Exercise 6-6. Implement a simple version of the #define processor (i.e., no arguments) suitable for use with C programs, based on the routines of this section. You may also find getch and ungetch helpful.

   Solution to Exercise 6-6

See also: K&R C — All Chapters Index | Complete C Programs List