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<head>
<title> function_exists.php </title>
<meta charset="UTF-8">
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</head>
<body>
<?php
function add($a,$b=2)
{
return $a + $b;
}
if(function_exists('add'))
{
echo add(3) . '<br>';
echo add(3,3) . '<br>';
}
if(function_exists('addxx'))
{
echo 'addxx<br>';
}
?>
</body>
</html>
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