How PHP obtains search keywords via visitor routing

 <?php class keyword{public function Getkeyword ($referer) {if Strpos ($referer, "http://www
		. baidu.com ") >-1) {$keyword = $this->getbaidukeyword ($referer);
		}else if (Strpos ($referer, "http://www.google.com") >-1) {$keyword = $this->getgooglekeyword ($referer);
		}else if (Strpos ($referer, "http://www.soso.com") >-1) {$keyword = $this->getsosokeyword ($referer);
		}else if (Strpos ($referer, "http://www.sogou.com") >-1) {$keyword = $this->getsogoukeyword ($referer);
	return $keyword;
		//By the antecedents of Baidu keyword Private function getbaidukeyword ($str) {$s = Strpos ($str, ' wd= ');
			if ($s >-1) {$str = substr ($str, $s +3);
			$e = Strpos ($str, ' & ');
			if ($e >-1) {$str = substr ($str, 0, $e);
		} $str = Rawurldecode ($STR);
	return $str;
		//Get Google keyword Private function getgooglekeyword ($str) {$s = Strpos ($str, ' &q= ');
			if ($s >-1) {$str = substr ($str, $s +3);
			$e = Strpos ($str, ' & ');
if ($e >-1) {				$str = substr ($str, 0, $e);
		} $str = Rawurldecode ($STR);
	return $str;
		//Get Soso keyword Private function getsosokeyword ($str) {$s = Strpos ($str, '? w= ');
			if ($s >-1) {$str = substr ($str, $s +3);
			$e = Strpos ($str, ' & ');
			if ($e >-1) {$str = substr ($str, 0, $e);
		} $str = Rawurldecode ($STR);
			}else{$s = strpos ($str, ' &w= ');
				if ($s >-1) {$str = substr ($str, $s +3);
				$e = Strpos ($str, ' & ');
				if ($e >-1) {$str = substr ($str, 0, $e);
			} $str = Rawurldecode ($STR);
	} return $STR;
		//Get Sogou keyword Private function getsogoukeyword ($str) {$s = Strpos ($str, ' query= ');
			if ($s >-1) {$str = substr ($str, $s +6);
			$e = Strpos ($str, ' & ');
			if ($e >-1) {$str = substr ($str, 0, $e);
		} $str = Rawurldecode ($STR);
	return $str; }