title: Include header files using command line option?
body: <p>Is it possible to specify extra header files to include from the command line (using GCC 4 / C++)?</p>
  
  <p>Or is there any other way files can be included except with #include?</p>
  
  <p>Background: I'm trying to compile a large code base on my own PC. The code is usually compiled in a cluster, with a complicated build system (SoftRelTools anybody?), which is intertwined with the operating system, such that it is virtually impossible to install it somewhere else (literally hundreds of makefiles and shell scripts, and hard coded paths to network drives). However, the actual code is fairly straightforward, and compiles fine, BUT it is missing a lot of includes (mostly a la "<code>include &lt;vector&gt;</code>" and "<code>include &lt;math.h&gt;</code>"). I'm guessing the build system takes care of this usually, but I have to go through the code and add the includes manually, which I'd rather avoid.</p>