Regex not working?

peschkaj has asked for the wisdom of the Perl Monks concerning the following question:

I finally got my script to work through .profile. However, it appears that my regular expression is not doing entirely what I think it should be. I expected it to dump if the user enters a value that is outside of a certain range. What seems to be happening is that the regex detects and works for single digits, but it does not catch anything more than a single digit. I have appended the script and the output below.

SCRIPT

#!/opt/perl5/bin/perl -w

use strict;

my @instances; my $i;
my $selection = 0; my $j = 0;

opendir OPHOME, "/opt/lnpsite" or die "Can't open /opt/lnpsite: $!\n";
my @files = sort(readdir(OPHOME));

foreach(@files){
    if (m/(op|nm)\d{2}$/) {
        push(@instances, $_);
    }
}

my $length = scalar(@instances);

while ($j != 1) { &chooser(); }
$selection = $selection - 1;

## COMPLETELY UNNECESSARY DEBUGGING CODE ##
###########################################
print "\nSELECTION IS: ",int($selection),".... LENGTH IS: $length\n";
print "j is: $j\n";


my $conn = "/opt/lnpsite/" . $instances[$selection] . "/scripts/setup_
+env";

symlink("$conn", ".setup_env");
open CHOSENENV, ">chosen_setup_env";
print CHOSENENV "$instances[$selection]";
close CHOSENENV;

sub chooser() {
    $i = 1;
    print "\nAvailable Instances\n===================\n";
    foreach(@instances) { print "  $i. ",$_,"\n"; $i++; }
    print "\nSelect an instance and press enter: ";
    $selection = <>;
    chomp($selection);

    if ($selection !~ /[1-$length]/) {
        print "\nIncorrect selection.  Try again.\n";
    } elsif ($selection !~ m/\d?/) {
        print "\nIncorrect selection.  Try again.\n";
    } else { $j = 1; }
}
[download]

OUTPUT

Available Instances
===================
  1. nm00
  2. nm01
  3. nm02
  4. nm09
  5. nm70

Select an instance and press enter: 111

SELECTION IS: 110.... LENGTH IS: 5
j is: 1
Use of uninitialized value in concatenation (.) or string at ./opSet.p
+l line 28, <> line 1.
Use of uninitialized value in string at ./opSet.pl line 32, <> line 1.
[download]

Thanks to all who have helped so much in already with this.

Comment on Regex not working? Select or Download Code

Replies are listed 'Best First'.
Re: Regex not working? by peschkaj (Pilgrim) on Aug 13, 2002 at 18:04 UTC
I combined Zaxo's answer and dws's answer to get something that worked quite nicely for me, and avoided the ugly return from redo unless. #!/opt/perl5/bin/perl -w use strict; my @instances; my $i; my $selection = 0; my $j = 0; opendir OPHOME, "/opt/lnpsite" or die "Can't open /opt/lnpsite: $!\n"; my @files = sort(readdir(OPHOME)); closedir OPHOME; foreach(@files){ if (m/(op\|nm)\d{2}$/) { push(@instances, $_); } } my $length = scalar(@instances); while ($j != 1) { &chooser( \@instances ); } open CHOSENENV, ">chosen_setup_env"; print CHOSENENV "$instances[$selection]"; close CHOSENENV; sub chooser { $i = 1; my ($arrayRef) = @_; print "\nAvailable Instances\n===================\n"; foreach(@$arrayRef) { print " $i. ",$_,"\n"; $i++; } print "\nSelect an instance and press enter: "; $selection = <>; chomp($selection); $selection -= 1; if ($selection < -1) { #!~ m/[1-$length]/) { print "\nIncorrect selection. Try again.\n"; } elsif ($selection > $length) { # !~ m/(\d{1})?/) { print "\nIncorrect selection. Try again.\n"; } else { $j = 1; } } [download]	[reply] [d/l]
Re: Regex not working? by Zaxo (Archbishop) on Aug 13, 2002 at 17:37 UTC
Your `chooser()` verification is incorrect. Simpler to do a numeric range check: `redo unless $selection > -1 and $selection < @instances;` [download] Your code would benefit from tightening the scope of lexical variables. `$selection` should be lexical within `sub chooser`, and a reference to the `@instances` array should be an argument to it. After Compline, Zaxo	[reply] [d/l]
Re: Regex not working? by dws (Chancellor) on Aug 13, 2002 at 17:54 UTC
Your problem is in `chooser()`. `if ($selection !~ /[1-$length]/) { ...` isn't doing what you expect. It will accept (or reject, though the effect is to accept) any string that includes at least one digit in the given range.	[reply] [d/l] [select]