@+ @-

@+   @-
有没人知道这两个是什么意思啊。
精通perl那上面有讲了点。
但没看懂。。

好像一个是放$1...$2这些
一个好像是放$&
不知道哪个是对应哪个
那放$&的这个
里面$(-或＋)［0....$#+］这里面是什么？

被我找到了。
$-[0]和$+[0] 代表当前匹配的正则表达式在被匹配的字符串中的起始和终止的位置 。

试了下。终于给我明白了。。。

http://perldoc.perl.org/perlvar.html

# @LAST_MATCH_START
# @-

$-[0] is the offset of the start of the last successful match. $-[n] is the offset of the start of the substring matched by n-th subpattern, or undef if the subpattern did not match.

Thus after a match against $_, $& coincides with substr $_, $-[0], $+[0] - $-[0] . Similarly, $n coincides with substr $_, $-[n], $+[n] - $-[n] if $-[n] is defined, and $+ coincides with substr $_, $-[$#-], $+[$#-] - $-[$#-] . One can use $#- to find the last matched subgroup in the last successful match. Contrast with $#+ , the number of subgroups in the regular expression. Compare with @+ .

This array holds the offsets of the beginnings of the last successful submatches in the currently active dynamic scope. $-[0] is the offset into the string of the beginning of the entire match. The nth element of this array holds the offset of the nth submatch, so $-[1] is the offset where $1 begins, $-[2] the offset where $2 begins, and so on.

After a match against some variable $var:

    * $` is the same as substr($var, 0, $-[0])
    * $& is the same as substr($var, $-[0], $+[0] - $-[0])
    * $' is the same as substr($var, $+[0])
    * $1 is the same as substr($var, $-[1], $+[1] - $-[1])
    * $2 is the same as substr($var, $-[2], $+[2] - $-[2])
    * $3 is the same as substr($var, $-[3], $+[3] - $-[3])

看看这儿：http://bbs.chinaunix.net/thread-769567-1-1.html

这些东西用到再查。