print "Enter the name of the files containing all the proteomic information: \n"; my $filename = ; unless( $filename =~ /\.pep?$/) #Checking if the file extension is .pep { die "File is not .pep file. Exiting. \n"; } open (DATA, $filename) or die "Cannot open $filename!\n"; my @arraydata = ; #all the information in the pep file is input into an array