G interface with some variable
declarations in it.

<h2>Manipulating Variables from Perl</h2>

Accessing a C global variable from Perl is easy---just reference it like a normal Perl variable.
Click <a href="runme.pl">here</a> to see a script that updates and prints some global variables.

<h2>Creating read-only variables</h2>

The <tt>%immutable</tt> and <tt>%mutable</tt> directives can be used to
specify a collection of read-only variables.  For example:

<blockquote>
<pre>
%immutable;
int    status;
doubl