===== Using the GNU C++ Compiler =====



==== Overview ====

[[ http://directory.fsf.org/devel/compilers/gcc.html | The GNU Compiler Collection ]]  (GCC) is an integrated collection of compilers for several languages,  including C, C++, Java and Fortran.


Our interest here is with the [[ http://directory.fsf.org/gpp.html | C/C++ compiler ]].


==== Syntax ====


The g++ command has the following syntax:


|   **g++** [**-**//option...//]  //file//... [//option// | //file//]... |

where //option// denotes an option or switch (see below)  and //file// denotes a file name.


==== Options ====


The list of valid options/switches for the g++ command includes  the following:

^Option^Purpose^
|c|Compiles without linking|
|D//name//=//definition//|Defines a symbol (as with ''%%#define%%'')|
|E|Stop after the preprocessing stage|
|g|Produce debugging information|
|I|Searches the given directory for "includes"|
|l//libname//|Searches the specified library when linking|
|o//filename//|Names the output file|
|M|Instead of preprocessing, output a rule suitable for use by ''%%make%%''|
|-help|Provides (some) help|
|-version|Displays the version number|

==== Examples ====


The following command compiles (but does not link) the C source file  named ''%%test.c%%'' and creates the file ''%%test.o%%'':



<code bash>
g++ -c test.c
</code>

The following command first defines the symbol ''%%DEBUG%%''  in the C++ source file named ''%%Demo.cpp%%'' and then  compiles and links it (creating an executable file  named ''%%Demo%%'').

<code bash>
g++ -DDEBUG=VERBOSE Demo.cpp -o Demo
</code>

The following command "includes" files from the directory  ''%%/myfiles/include%%'' in addition to the standard INCLUDE  directory.

<code bash>
g++ -I/myfiles/include Demo.cpp -o Demo
</code>

The following commands first compile the source files for a small  application (written in C) and then links them into an executable named  ''%%example%%''.

<code bash>
g++ -c account.c
g++ -c example.c
g++ example.o account.o -o example
</code>


==== Error and Warning Messages ====


Error and warning messages generated by the GCC are often less than  clear.  There are several places you can go for help, including:

 
  * [[ http://www.network-theory.co.uk/docs/gccintro/gccintro_94.html | 
 Compiler Error Messages ]]  (courtesy of Network Theory, Ltd.)
  * [[ http://users.csc.calpoly.edu/~jdalbey/101/Resources/errormessages.html | 
 Common Error Messages ]] (courtesy of California Polytechnic State University)