in reply to matching &printing S variable of an array

$peptide remains blank because it is never initialized.

To avoid such errors, always start your scripts with use strict; use warnings;

Add

my $peptide = $_;
before the start of your foreach loop and see if that helps.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

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