-----------------------------------------
Chapter 1: A Tutorial Introduction
-----------------------------------------

Curious, I assumed I'd need the ``gcc`` command for this book.
The book uses ``cc``. Looks like ``cc`` is the Unix C compiler, while
``gcc`` ships with the GNU Compiler OS.

The book recommends the old style, apparently. ``C99`` recommends that both
the ``main`` should be preceded by the explicit return type, and that the
argument list should also be explicit. The program builds without them,
but you get warnings otherwise.

Hence, the ``hello_world.c`` program becomes:

.. code:: c
    :linenos:

    #include <stdio.h>

    int main(void)

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

Curiously enough, C doesn't define standards for exit codes. This is platform
dependent.