You've finished your second week of learning how to program with Perl. By now, you know enough about Perl to consider yourself an accomplished Perl programmer.
The third week covers the rest of the Perl library functions, describes some of the more esoteric concepts of the language, and introduces some features unique to version 5 of Perl. Here's a summary of what you'll learn.
Day 15, "System Functions," describes the functions that work with lists and array variables.
Day 16, "Command-Line Options," describes the options you can supply with Perl to control how your program runs.
Day 17, "System Variables," describes the built-in variables that are included automatically as part of every Perl program.
Day 18, "References in Perl 5," describes the use of Perl references and the concept of pointers.
Day 19, "Object-Oriented Programming in Perl," covers how to construct objects in Perl and how to use OOP features offered by Perl.
Day 20, "Miscellaneous Features of Perl," covers some of the more exotic or obscure features of the language.
Finally, Day 21, "The Perl Debugger," shows you how to use the Perl debugger to quickly discover errors.
By the end of the third week, you'll know all the features and capabilities of Perl.