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<h1>Directive #if</h1>
<hr />
<dl class='group--doc'>
<dt class='head--type'><span class='homogen--type'>Directive</span>
<span class='homogen--name'><b>#if</b></span>
</dt>
<dd><p><code class='directive'>#if</code><br>
<code class='directive'>#elif</code><br>
<code class='directive'>#elseif</code><br>
<code class='directive'>#else</code><br>
<code class='directive'>#endif</code></p></dd>
<dt class='head--doc'>Description</dt>
<dd class='body--doc'>
<p>The #if directive causes conditional compiling of code depending on
the expression after the #if directive. That is, if the expression
is true, the code up to the next #else, #elif, #elseif or #endif is
compiled. If the expression is false, that code will be skipped.
If the skip leads up to a #else, the code after the else will be
compiled. #elif and #elseif are equivialent and causes the code that
follow them to be compiled if the previous #if or #elif evaluated
false and the expression after the #elif evaluates true.
</p>
<p>Expressions given to #if, #elif or #endif are special, all identifiers
evaluate to zero unless they are defined to something else. Integers,
strings and floats are the only types that can be used, but all lpc
operators can be used on these types.
</p>
<p>Also, two special functions can be used, defined() and efun().
defined(<identifer>) expands to '1' if the identifier is defined,
'0' otherwise. efun(<identifier>) expands to '1' if identifer is
an efun, '0' otherwise.</p>
</dd>
<dt class='head--doc'>Example</dt>
<dd class='example'><pre>
<tt><p>#if 1<br />
<dl class='group--doc'><dd>write("foo");<br />
</dd>
</dl>#else<br />
<dl class='group--doc'><dd>write("bar");<br />
</dd>
</dl>#endif<br />
</p>
<p>#if defined(FOO)<br />
<dl class='group--doc'><dd>write(FOO);<br />
</dd>
</dl>#elif defined(BAR)<br />
<dl class='group--doc'><dd>write(BAR);<br />
</dd>
</dl>#else<br />
<dl class='group--doc'><dd>write("default");<br />
</dd>
</dl>#endif<br />
</p>
<p>#if !efun(write_file)<br />
inherit "simulate.lpc"<br />
#endif<br />
<br />
</p>
</tt></pre></dd></dl>
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