Learning GNU C

Learning GNU C

Ciaran O'Riordan

Copyright © 2002 Ciaran O'Riordan

This file is a C programming tutorial using the GNU C compiler and GNU Libc.

Copyright © 2002 Ciaran O'Riordan.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

with the no Invariant Sections, with the Front-Cover Texts being "Richard Stallman Rules", and with the Back-Cover Texts being "This is a Free book, Free as in Freedom. Permission is granted to copy, distribute, and edit this book under the GNU Free Documentation License".

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Table of Contents

Preface

1. Target Audience

2. Scope of this text

3. Why learn C?

4. Why use GNU?

5. Why Free Software?

6. References to persons

1. Introduction to C

1.1. What are Programming Languages?

1.2. What is C?

1.3. Programming Tools

1.4. Introducing GCC

1.5. Who defines Valid C?

1.5.1. "K&R" C

1.5.2. ISO C

1.5.3. C99

1.5.4. GNU C

1.5.5. Choosing a Dialect

1.5.6. Future Standards

1.6. Conclusion

2. Staring With Functions

2.1. What are functions?

2.2. A Line-by-Line Dissection

2.3. Comments

2.4. Making your own Functions

2.5. Multiple Files

2.6. Header Files

2.7. A Larger (non)Program

2.8. Another new Function

2.9. Primer Summary

3. Data and ｅxpressions

3.1. Bicycle Dissection

3.2. Data Types

3.3. Another Example of Assignment

3.4. Quick Explanation of printf()

3.5. Simple arithmetic

3.6. Global Variables

3.7. Static Variables

3.8. Constant Variables

4. Flow Control

4.1. Branching

4.2. if ... else

4.3. Loops

4.4. while

4.5. for

4.6. do .. while

4.7. Switch

4.8. The Conditional Operator

4.9. break & continue

5. Pointers

5.1. The Basics

5.2. The Address of a Variable

5.3. Pointers as Function Arguments

5.4. Pointer Arithmetic

5.5. Generic Pointers

6. Structured Data Types

6.1. What is Structured data?

6.2. Arrays

6.3. Declaring and Accessing Arrays

6.4. Initialising Arrays

6.5. Multidimensional Arrays

6.6. Arrays of Characters (Text)

6.7. Defining data types

6.8. Structured Data

6.9. Unions

7. Run-time Memory Allocation

7.1. Why you need this

7.2. Dynamic Memory Functions

7.3. Run-time Memory Summary

8. Strings and File I/O

8.1. Introduction

9. Storage Classes

9.1. What are Storage Classes?

9.2. auto

9.3. static

9.4. extern

9.5. register

9.6. the restrict type qualifier

9.7. typedef

10. The C Preprocessor

10.1. What is the C Prepressor

10.2. What is it used for?

10.3. Some sample macros

10.4. Caveats for macros

10.5. Are macros necessary?

10.6. Replacing Simple Macros

10.7. Replacing Complex Macros

11. Variable Length Arguments

11.1. What are Variable Length Arguments?

12. Tricks with Functions

12.1. What are Virtual Functions?

12.2. Nesting functions

12.3. The Benefits of Nested Functions

12.4. Declaring and Defining Nested Functions

12.5. Scope

13. Taking Command Line Arguments

13.1. How does C handle command line arguments?

13.2. Argp

13.3. Using More of the Argp Functionality

13.4. Environment Variables

14. Using and Writing Libraries

14.1. What are Libraries?

14.2. Using Libraries

14.3. Stages of Compilation

14.4. Writing a library

14.5. Dynamic or Static

15. Writing Good Code

15.1. Readability

16. Speed

16.1. About Optimising

16.2. What are function attributes?

16.3. Function Attribute Syntax

16.4. What are pure and const?

A. GNU Free Documentation License

A.1. 0. PREAMBLE

A.2. 1. APPLICABILITY AND DEFINITIONS

A.3. 2. VERBATIM COPYING

A.4. 3. COPYING IN QUANTITY

A.5. 4. MODIFICATIONS

A.6. 5. COMBINING DOCUMENTS

A.7. 6. COLLECTIONS OF DOCUMENTS

A.8. 7. AGGREGATION WITH INDEPENDENT WORKS

A.9. 8. TRANSLATION

A.10. 9. TERMINATION

A.11. 10. FUTURE REVISIONS OF THIS LICENSE

A.12. ADDENDUM (How to use this License for your documents)

List of Examples

1-1. C vs. Assembly language

1-2. tiny.c

1-3. tiny2.c

2-1. hello.c

2-2. hello2.c

2-3. three_functions.c

2-4. main.c

2-5. display.c

2-6. display.h

2-7. prices.c

2-8. prices.h

3-1. bicycles.c

3-2. sizeof_types.c

3-3. displaying_variables.c

3-4. more_printf.c

3-5. wages.c

4-1. using_if.c

4-2. cows2.c

4-3. guess_my_number.c

4-4. for_ten.c

4-5. guess_my_number.c

4-6. apples.c

5-1. pointers_are_simple.c

5-2. swap_ints.c

5-3. generic_pointer.c

6-1. first_arrays.c

6-2. initialise_array.c

6-3. number_square.c

6-4. person_struct.c

9-1. list_squares.c

9-2. battleships.c

10-1. box_of_stars.c

10-2. max_macro.c

10-3. max_macro_problem.c

12-1. virtual_function.c

12-2. simple nested function

13-1. list_args.c

13-2. simple_argp.c

13-3. better_argp.c

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		Preface