Programming :: Perl - Use Of Uninitialized Value In Split?

I'm currently teaching myself perl. I'm trying to write a program that unscrambles words by comparing each element in the array. There is an input file where you type the words to be unscrambled and there is a word list file containing approximately 1300 words. After everything has been processed the program is supposed to paste those words to an output file.

Code:
#!/usr/local/bin/perl
#use strict; #always add this in the beginning of code.
#use warnings; #always add this in the beginning of code.
#open(INFILE, '<', 'sample.txt'); # For reading
#open(INFILE, '>', 'sample.txt'); # For writing
#open(INFILE, '>>', 'sample.txt'); # To append .....