$str =<<<STR
the theory
my myselef
your yourselef
STR;
$reg = '/^([a-zA-Z]+)\s*\1[a-zA-Z]*\s?$/m';
preg_match_all($reg, $str, $result);
print_r($result);Array
(
[0] => Array
(
[0] => the theory
[1] => my myselef
[2] => your yourselef
) [1] => Array
(
[0] => the
[1] => my
[2] => your
))windows 中,换行是 \r\n
the theory
my myselef
your yourselef
STR;
$reg = '/^([a-zA-Z]+)\s*\1[a-zA-Z]*\s?$/m';
preg_match_all($reg, $str, $result);
print_r($result);Array
(
[0] => Array
(
[0] => the theory
[1] => my myselef
[2] => your yourselef
) [1] => Array
(
[0] => the
[1] => my
[2] => your
))windows 中,换行是 \r\n
$str = "the theory\nmy myselef\nyour yourselef";
$匹配\n前或字串结尾,/r 也是一个字符,且不在[a-zA-Z]范围,但最后一行是字串结尾,就匹配到了
the theory
my myselef
your yourselef
STR;
数据的最后一行后面没有换行
$str =<<<STR
the theory
my myselef
your yourselefSTR;数据的最后一行后面有换行