perl学习遇到问题,提示used only once:$s1='bbb';$s2='aaa';$s3=$s2.$s2;print $s3;提示：Name "main::s1" used only once:possible typo at C:\perlt\2.pl line 3.

perl学习遇到问题,提示used only once:$s1='bbb';$s2='aaa';$s3=$s2.$s2;print $s3;提示：Name "main::s1" used only once:possible typo at C:\perlt\2.pl line 3.
perl学习遇到问题,提示used only once:
$s1='bbb';$s2='aaa';$s3=$s2.$s2;print $s3;提示：Name "main::s1" used only once:possible typo at C:\perlt\2.pl line 3.

perl学习遇到问题,提示used only once:$s1='bbb';$s2='aaa';$s3=$s2.$s2;print $s3;提示：Name "main::s1" used only once:possible typo at C:\perlt\2.pl line 3.
use strict;
use warnings;
my $s1 = 'bbb';
my $s2 = 'aaa';
my $s3 = $s2.$s2;
print $s3;
C:\Users\Hunter\Documents\Perl>perl dot.pl
aaaaaa
没有问题呀