Floating Octothorpe

The C Programming Language: Preface

C is by any standard a relatively old programming language; despite this it is still widely used. In fact C just missed out on a top ten spot in this years Stack Overflow Developer Survey.

For a long time now I've been meaning to go through The C Programming Language by Brian Kernighan and Dennis Ritchie. Although the most recent edition of the book is older than I am, it still has a reputation for being one of the best ways to learn C.

Over the next few posts I'm going to go over each of the following chapters from the book:

  1. A Tutorial Introduction
  2. Types, Operators, and Expressions
  3. Control Flow
  4. Functions and Program Structure
  5. Pointers and Arrays
  6. Structures
  7. Input and Output
  8. The UNIX System Interface

I'm planning to keep sample code on GitHub. If you're interested in following along, the rest of this post is going to quickly go over compiling a simple hello world program on CentOS or Debian.

Installing GCC

The GNU Compiler Collection (GCC) is a free and open source compiler system which is available on most Linux distributions. On Debian it can be installed using apt-get:

sudo apt-get install gcc

Alternatively on Red Hat based distributions like CentOS yum can be used:

sudo yum install gcc

If everything goes well, you should now be able to run gcc --version:

$ gcc --version
gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-16)
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Hello World

Once GCC is installed you can test it with a simple hello world example. First create a text file called hello.c with the following contents:

#include <stdio.h>

main()
{
    printf("hello, world\n");
}

This can then be compiled with gcc:

gcc hello.c

Compiling the source code will produce an executable binary, by default the binary will be called a.out. Running this should print hello, world to stdout:

$ ./a.out
hello, world

Note: a.out is short for assembler output, this filename default actually pre-dates the first edition of UNIX!