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<h1>22. Virtuoso Functions Guide - if</h1>
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<div id="text">
<h2>if</h2>
<div class="refpurpose">If the boolean value is true then calculates one expression, otherwise calculates another expression.</div>
<div class="funcsynopsis">
<span class="funcdef">any <span class="function">if</span>
</span>
(<span class="paramdef">
<span class="parameter">test</span> boolean</span>,
<span class="paramdef">
<span class="parameter">then_branch</span> any</span>,
<span class="paramdef">
<span class="parameter">else_branch</span> any</span>);
</div>
<div class="refsect1">
<div class="refsect1title">Description</div>
<p>
This function calculates the value of <span class="computeroutput">test</span> argument.
If the value is true, the function calculates the <span class="computeroutput">then_branch</span>
expression and returns its value.
If the value is false, the function calculates the <span class="computeroutput">else_branch</span>
expression and returns its value.
</p>
<p>
Note that unlike other programming languages, <span class="computeroutput">else_branch</span>
is required argument, not optional.
</p>
<p>
This function is used in the implementation of
"IF" control operator in XQUERY,
so you will probably use that operator in XQUERY expressions, not the function.
This function may be useful in XPATH expressions and in XSLT stylesheets.
It is not a part of library of standard XQUERY 1.0 functions.
</p>
</div>
<div class="refsect1">
<div class="refsect1title">Parameters</div>
<div class="refsect2">
<span class="refsect2title">test – </span>
Boolean value used to choose an expression to execute</div>
<div class="refsect2">
<span class="refsect2title">then_branch – </span>
Expression which is calculated if <span class="computeroutput">test</span> argument is true</div>
<div class="refsect2">
<span class="refsect2title">else_branch – </span>
Expression which is calculated if <span class="computeroutput">test</span> argument is false</div>
</div>
<div class="refsect1">
<div class="refsect1title">Return Types</div>
<p>Any</p>
</div>
<div class="refsect1">
<div class="refsect1title">Examples</div>
<a name="xpf_ex_if" />
<div class="example">
<div class="exampletitle" />
<p>These two expressions are equivalent,
but first may be used in any XPATH while second is written in XQUERY syntax:</p>
<div>
<pre class="screen">
if (2 * 2 = 4, 'I think so', 'Unbelievable!')
IF 2 * 2 = 4 THEN 'I think so' ELSE 'Unbelievable!'
</pre>
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<div class="refsect1">
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