ument, and <code>-f</code> takes a
string (in particular, a filename) as an argument.  Users can use a
library to help parse the commandline and store the flags in some data
structure.</p>

<p>Gflags, the commandline flags library used within Google,
differs from other libraries,
such as <code>getopt()</code>, in that flag definitions can be
scattered around the source code, and not just listed in one place
such as <code>main()</code>.  In practice, this means that a single
source-code file will define and 