I'm not quite sure what is actually implemented there, but the issue appears to be in:

until($cust =~ <\w{3,4}>) {

You should get your expected behavior by changing that to:

until($cust =~ /\w{3,4}/) {

since you are trying to match against a regular expression. I'd also add start and end anchors, as your expression as written would also match a 17-letter expression - it contains multiple 3 and 4 letter sets.

until($cust =~ /^\w{3,4}$/) {

As a side note, you can use last to do flow control and reduce your code repetition, as well as use a heredoc: 

use strict;
use warnings;

while (1) {
    print "Customer abbreviation:         ";
    my $cust = <STDIN>;
    print "\n";
    chomp ($cust);
    
    last if $cust =~ /\w{3,4}/;
    
    print <<EOT;
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!                                        !!!
!!! ABBREVIATION MUST BE 3 OR 4 CHARACTERS !!!
!!!                                        !!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

EOT
}

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In reply to Re: problem with pattern match by kennethk
in thread problem with pattern match by ddrew78

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