\section{Timers}

\cgal\ provides classes for measuring the user process time and the real time.
The class \ccc{CGAL::Timer} is the version for the user process time and
the class \ccc{CGAL::Real\_timer} is the version for the real time.

Instantiations of both classes are objects with a state. The state is
either {\em running\/} or it is {\em stopped}. The state of an object
\ccc{t} is controlled
with \ccStyle{t.start()} and \ccStyle{t.stop()} . The timer counts the
time elapsed since its creation or last reset. It counts only the time
where it is in the running state. The time information is given in seconds.
The timer counts also the number of intervals it was running, i.e. it 
counts the number of calls of the \ccc{start()} member function since the 
last reset. If the reset occurs while the timer is running it counts as the
first interval.

\section{Memory Size}

\cgal\ provides access to the memory size used by the program with the
\ccc{CGAL::Memory_sizer} class.  Both the virtual memory size and the
resident size are available (the resident size does not account for
swapped out memory nor for the memory which is not yet paged-in).

\section{Profiling}

\cgal\ provides a way to count the number of times a given line of code
is executed during the execution of a program.  Such
\ccc{CGAL::Profile_counter} counters can be added at critical place in the
code, and at the end of the execution of a program, the count is printed on
\ccc{std::cerr}.  A macro \ccc{CGAL_PROFILER} can be used to conveniently place
these counters anywhere.  They are disabled by default and activated by the
global macro \ccc{CGAL_PROFILE}.

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