求正则婚配tab，t貌似也会匹配空格呢

$s = ' 	'; //一个空格加一个制表符

echo current(unpack('H*', $s)); //2009 20是空格的十六进制内码，09是Tab键的十六进制内码



preg_match("/\t+/", $s, $r);

echo current(unpack('H*', $r[0])); //得到 09



preg_match("/ +/", $s, $r);

echo current(unpack('H*', $r[0])); //得到 20



preg_match("/\s+/", $s, $r);

echo current(unpack('H*', $r[0])); //得到 2009