$re = '/(?<=\/)[^\/]*(?=\?)/';
$str = '<html>
<body>
<iframe src=https://zarabol.rediff.com/widget/end-of-cold-war-salman-hugs-abhishek-bachchan?search=true&header=true id=rediff_zarabol_widget name=rediff_zarabol_widget scrolling=auto transparency= frameborder=0 height=500 width=100%>
</iframe>
</body>
</html>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php