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<h2>
<span class="refentrytitle">#ifdef</span>
</h2>
<p>#ifdef —
Conditional reading of code.
</p>
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<div class="refsect1" title="Description">
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<h2>Description</h2>
<p>
If a macro is defined then <span class="emphasis"><em>#ifdef</em></span> can
incorporate text into an orchestra upto the next
<span class="emphasis"><em>#end</em></span>.
This is similar to, but independent of, the <a class="link" href="ScoreMacros.html" title="Score Macros"><em class="citetitle">macro system in the score
language</em></a>.
</p>
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<div class="refsect1" title="Syntax">
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<h2>Syntax</h2>
<pre class="synopsis"><span class="command"><strong>#ifdef</strong></span> NAME</pre>
<pre class="synopsis">....</pre>
<pre class="synopsis"><span class="command"><strong>#else</strong></span> </pre>
<pre class="synopsis">....</pre>
<pre class="synopsis"><span class="command"><strong>#end</strong></span> </pre>
</div>
<div class="refsect1" title="Performance">
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<h2>Performance</h2>
<p>
Note that the <span class="emphasis"><em>#ifdef</em></span> can be nested, like in the C preprocessor language.
</p>
</div>
<div class="refsect1" title="Examples">
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<h2>Examples</h2>
<p>
Here is a simple example of the conditional.
</p>
<div class="example">
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<p class="title">
<strong>Example 14. Simple example of the #ifdef form.</strong>
</p>
<div class="example-contents">
<pre class="programlisting">
<span class="omacro">#define</span> debug
<span class="oblock">instr</span> 1
<span class="omacro">#ifdef</span> debug
<span class="opc">print</span> "calling oscil"
<span class="omacro">#end</span>
a1 <span class="opc">oscil</span> 32000,440,1
out <span class="opc">a1</span>
<span class="oblock">endin</span></pre>
</div>
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<p><br class="example-break" />
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<div class="refsect1" title="See Also">
<a id="idp12401544"></a>
<h2>See Also</h2>
<p>
<a class="link" href="dollar.html" title="$NAME"><em class="citetitle">$NAME</em></a>,
<a class="link" href="define.html" title="#define"><em class="citetitle">#define</em></a>,
<a class="link" href="ifndef.html" title="#ifndef"><em class="citetitle">#ifndef</em></a>.
</p>
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<div class="refsect1" title="Credits">
<a id="idp12403576"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: John ffitch</td>
</tr>
<tr>
<td>University of Bath/Codemist Ltd.</td>
</tr>
<tr>
<td>Bath, UK</td>
</tr>
<tr>
<td>April 2005</td>
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<p>
</p>
<p>New in Csound5 (and 4.23f13)</p>
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