I am trying to grasp the regular expressions and various uses for them. I am working on a problem where I am given a string of letters and have to use a regular expression to find the sequences that starts with ATG and ends with TAG, TAA, or TGA. I am having trouble figuring out the regular expression that would search for each of these endings in a single expression. Here is what I have so far 

#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;

#insert sequence
my $seq = 'AATGGTTTCTCCCATCTCTCCATCGGCATAAAAATACAGAATGATCTAACGAA';

#find codons
while ($seq =~ m/ATG(.*)(TAG|TAA|TGA)/g){

#print codons
                print $1, "\n";
                }

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but I am not getting the correct output, instead getting that the $1 is unspecified. Any suggestions? I would really like to understand how this sort of regular expression works. Thank you!

In reply to Regular expressions by lairel

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