You're welcome. The use strict I referred to brings in the strict Perl module (technically, it's a pragma) into your program, which restricts it from doing certain things. You can read about it here or here.
In a (very simplified) nutshell, it does three things:
- It disallows using variables which haven't been declared in some fashion, such as with my, our, use vars, etc. This would've caught your upper/lower case problem since there was no declaration for $LASTNAME.
- It generates an error if you use a bareword (i.e., an identifier with no type symbol like $, @, and %).
- It prevents you from using symbolic references. That's a bit of an advanced topic; at this stage you should just avoid them unquestioningly. ;-)
It's the collective wisdom of the Perl community that any script longer than a few lines should always begin with
use strict. I heartily agree.