PHP在字符串中查找http：//或www [duplicate]

function make_clickable($sText) {
    $sClickText = str_replace(\' www.\', \' http://www.\', $sText);
    $sClickText = preg_replace(\"/([\\s])?(http|ftp|https)([\\:\\/\\/])([^\\s]+)/i\", \" <a href=\\\"$2$3$4\\\" target=\\\"_blank\\\">$2$3$4</a>\",$sClickText);
    return $sClickText;
}