Perl: I do not pass parameters to usage() and @_ is defined yet ???

devid33

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#!/usr/bin/perl

use Getopt::Long;
 
$l=@ARGV;
 
print "The number of args is " . @ARGV;print "\n"; 
 
my  $bool= GetOptions('help|?' => \$help, 'url=s' => \$url, 'size=i' => \$size);
 
;

if ( !$bool    or $l < 1 || defined $help ){

&usage();
 
print "=======\n";

print "THE END";

{ 

  if (@_ ){

  print "Unknown option: @_\n"}

  print "usage: program [--url URL] [--size SIZE] [--help|-?]\n";
 
}

OUTPUT:
=======
C:\>perld.pl --url www --size 15 -david -fass
The number of args is 6
Unknown option: david
Unknown option: fass

usage: program [--url URL] [--size SIZE] [--help|-?]
=======

please explain why the "additional arguments of perld.pl" are passed through sub usage() to @_????
but I call to sub usage() without parameters????????!!!!!!!!!

KevinADC

@_ is global. It will display whatever it's last values were. Since you did not pass any arguments to usage(), @_ is still the values of the paramaters you passed to the script.

Perl: I do not pass parameters to usage() and @_ is defined yet ???

re: Perl: I do not pass parameters to usage() and @_ is defined yet ???

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