Getopt::Long and default number

[mrborisguy]

I've started using Getopt::Long for a little script I'm creating. I'm having trouble figuring out how to give an option a default value if it is specified. For example:

shell$ progname
  $opt == 0
shell$ progname --opt
  $opt == 100
shell$ progname --opt 7
  $opt == 7

Or more verbosely, if --opt isn't specified, I want it to be 0. If --opt is specified, but not given any number, I want $opt to hold 100, and if --opt is specified with a number, I want $opt to hold the number specified.

This is probably really easy, but I must be missing it. Has anybody done this before?

    -Bryan

[jimbojones]

Hi
I think you want the ":" signifier when identifying your options. This says the value for the option is optional. If the option is present without a value, it takes the number indicatied after the ":" ; otherwise it takes the user-supplied value. This is in the POD in the section "Summary of Option Specifications"

use Getopt::Long;

my $opt = 0;

GetOptions ("opt:100" => \$opt );

print "Opt is:\t$opt\n";

My test runs give:

>opt.pl --opt
Opt is: 100

>opt.pl --opt 7
Opt is: 7

>opt.pl
Opt is: 0

HTH
- j

[mrborisguy]

Bingo! Thanks! ++

    -Bryan

[izut]

Try this:

my $opt = "0";
$result = GetOptions ("opt:s" => \$opt,);
$opt = 100 if ($opt eq "");

I'm pretty sure there are some better way to perform this task, but can't figure out how right now.