PHP keyword highlighting

Replace the specified keywords and highlight them on the html page

function highlight($sString, $aWords) {
if (!is_array ($aWords) || empty ($aWords) || !is_string ($sString)) {
return false;
}
$sWords = implode ('|', $aWords);
return preg_replace ('@b('.$sWords.')b@si', '< ;strong style="background-color:yellow">$1', $sString);
}

PHP