You have to specify that you are looking at the beginning of the line for the "yEs" or that spaces in front do not matter.

This question often comes up in the context of "how do I write a simple command line loop"?

There are very few times in 'C' or in Perl where the comma operator makes sense to use, but this is one of them! This is an interactive thing that you can play with...go for it! Fiddle with the regex and see what it does!

Some Monks prefer more complex formulations of this command line loop algorithm. I think the important part here is for you to understand how to "drive the regex part". 

#!/usr/bin/perl -w
use strict;

while ( (print "Enter some text: "), 
        (my $line=<STDIN>) !~ /^\s*q(uit)?\s*$/i  
      )
{
   next if $line =~ /^\s*$/; #blank line just re-prompts
   chomp ($line);    # a real app would probably do this
   print "$line\n";  # although here I just add it back
}
print "program exited\n";

__END__
C:\TEMP>stdcmdline.pl
Enter some text: 25436
25436
Enter some text: QuIT
progam exited

C:\TEMP>stdcmdline.pl
Enter some text: quI
quI
Enter some text: Q
progam exited

C:\TEMP>stdcmdline.pl
Enter some text: asdf
asdf
Enter some text: qu
qu
Enter some text: QuIT
program exited

C:\TEMP>stdcmdline.pl
Enter some text: quited
quited
Enter some text: 3245
3245
Enter some text: Q
program exited

C:\TEMP>stdcmdline.pl
Enter some text: q
program exited

C:\TEMP>stdcmdline.pl
Enter some text:        quit
program exited

[download]

In reply to Re: conditional regex by Marshall
in thread conditional regex by Anonymous Monk

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