perl .= 操作符

[root@master Webqq]# cat k4.pl 
$a=3;
$b=4;
print "$a is $a
";
print "$b is $b
";
$a .=$b;
print "$a is $a
";
print "$b is $b
";
[root@master Webqq]# perl k4.pl 
$a is 3
$b is 4
$a is 34
$b is 4