正则的问题

[ 02:30:32 root@test2 perl]$perl -e 'open(HD,"reg1.pl");while(<HD>){print if /a{2,4}b/;}'
$_salary='aabcdZA';
aab
aaab
aaaaab
aaaaaab
aaaaaaab
aaaaaabc
[ 02:30:35 root@test2 perl]$cat reg1.pl
#!/usr/bin/perl
#auth youcz March 2nd Wednesday
$_=5050;
$temp='aa';
$_salary='aabcdZA';
$_salary=~tr/a-z/A-Z/;
print $_salary;
aab
aaab
aaaaab
aaaaaab
aaaaaaab
abc
aaaaaabc

能解释下匹配原则吗，为什么都打出来了？

本帖最后由 jason680 于 2011-03-17 14:52 编辑





printf if /a{2,4}b/

aab  ==> match
aaab  ==> match
aaaaab  ==> match
aaaaaab  ==> match
aaaaaaab  ==> match
abc  ==> not match
aaaaaabc  ==> match