Comparing return value of include (bug #15438)

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@164487 c90b9560-bf6c-de11-be94-00142212c4b1

language/control-structures.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.97 $ -->
+<!-- $Revision: 1.98 $ -->
  <chapter id="language.control-structures">
   <title>Control Structures</title>
 
@@ -1424,6 +1424,29 @@ if ($condition) {
     variables within those tags and they will be introduced at whichever point
     the file was included.
    </simpara>
+   <para>
+    Because <function>include</function> is a special language costruct,
+    parentheses are not needed around its argument. Take care when comparing
+    return value.
+    <example>
+     <title>Comparing return value of include</title>
+     <programlisting role="php">
+<![CDATA[
+<?php
+// won't work, evaluated as include(('vars.php') == 'OK'), i.e. include('')
+if (include('vars.php') == 'OK') {
+    echo 'OK';
+}
+
+// works
+if ((include 'vars.php') == 'OK') {
+    echo 'OK';
+}
+?>
+]]>
+     </programlisting>
+    </example>
+   </para>
    <para>
     <note>
      <simpara>