[root@stationx ch2-regular]# cat perl-grep4.pl

#!/bin/perl # perl-grep4.pl my $pattern = shift @ARGV; my $regex = eval { qr/$pattern/ }; die "Check your pattern! $@" if $@; while(<>)         {         if(m/$regex/)                 {                 print "$_";                 print "\t\t\$&: ",                 substr( $_, $-[$i],$+[$i] - $-[$i] ),                 "\n";                 foreach my $i ( 1 .. $#- )                         {                         print "$#-\n";                         print "\t\t\$$i: ",                         substr( $_,$-[$i],$+[$i] - $-[$i] ),                         "\n";                         }                 }         }

[root@stationx ch2-regular]# perldoc -t perl| perl perl-grep4.pl "\b(\S)(\S)\1\b"

        the Comprehensive Perl Archive

                $&: www                 $1: w                 $2: w               the Perl Mongers                 $&: www                 $1: w                 $2: w [root@stationx ch2-regular]# @-和@+两个数组非常的神奇，两者保存的是matched内容的offset（偏移量）          也就是说每个match内容的起始offset值放置在@-数组中，结束offset值放置在@+数组中          说白了@-和@+两个数组保存的是一系列的值。          @-数组的第一个元素是matche内容的起始offset，@+数组的第一个元素是match内容的结尾offset          随后才是$1,$2...的offset值。