<sect1 id="gcc"><title>Using GCC with Cygwin</title>

<sect2 id="gcc-cons"><title>Console Mode Applications</title>

<para>Use gcc to compile, just like under UNIX.
Refer to the GCC User's Guide for information on standard usage and
options.  Here's a simple example:</para>

<example>
<title>Building Hello World with GCC</title>
<screen>
<prompt>C:\&gt;</prompt> <userinput>gcc hello.c -o hello.exe</userinput>
<prompt>C:\&gt;</prompt> <userinput>hello.exe</userinput>
Hello, World

<prompt>C:\&gt;</prompt>
</screen>
</example>

</sect2>

<sect2 id="gcc-gui"><title>GUI Mode Applications</title>

<para>Cygwin allows you to build programs with full access to the
standard Windows 32-bit API, including the GUI functions as defined in
any Microsoft or off-the-shelf publication.  However, the process of
building those applications is slightly different, as you'll be using
the GNU tools instead of the Microsoft tools.</para>

<para>For the most part, your sources won't need to change at all.
However, you should remove all __export attributes from functions
and replace them like this:</para>

<screen>
int foo (int) __attribute__ ((__dllexport__));

int
foo (int i)
</screen>

<para>For most cases, you can just remove the __export and leave it at
that.  For convenience sake, you might want to include the following
code snippet when compiling GUI programs.  If you don't, you will want
to add "-e _mainCRTStartup" to your link line in your Makefile.</para>

<screen>
#ifdef __CYGWIN__
WinMainCRTStartup() { mainCRTStartup(); }
#endif
</screen>

<para>The Makefile is similar to any other UNIX-like Makefile,
and like any other Cygwin makefile.  The only difference is that you use
<command>gcc -mwindows</command> to link your program into a GUI
application instead of a command-line application.  Here's an example:</para>

<screen>
myapp.exe : myapp.o myapp.res
	gcc -mwindows myapp.o myapp.res -o $@

myapp.res : myapp.rc resource.h
	windres $< -O coff -o $@
</screen>

<para>Note the use of <filename>windres</filename> to compile the
Windows resources into a COFF-format <filename>.res</filename> file.
That will include all the bitmaps, icons, and other resources you
need, into one handy object file.  Normally, if you omitted the "-O
coff" it would create a Windows <filename>.res</filename> format file,
but we can only link COFF objects.  So, we tell
<filename>windres</filename> to produce a COFF object, but for
compatibility with the many examples that assume your linker can
handle Windows resource files directly, we maintain the
<filename>.res</filename> naming convention.  For more information on
<filename>windres</filename>, consult the Binutils manual.  </para>

</sect2>
</sect1>
