Re^2: Question: Is undef a valid argument?

Sorry,

Spoke too soon.

None of what you sggested works.

#! /usr/bin/perl
use strict;
use warnings;

sub p1 {
    my $n1;
    $n1=scalar(@_);
    if  (@_) {
        print "Has elements\n";    
    }
    
    print "1. Parameters to the sub p1 $n1\n";
    my $p1=shift;
    if  (@_) {
        print "Has elements\n";    
    }
    else {
        print "Has no elements\n";    
    }
    print "2. p1=$p1\n";
}
p1 $ARGV[0];
[download]

Try passing nothing to the script you will see it still states one argument.

Comment on Re^2: Question: Is undef a valid argument? Download Code

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Re^3: Question: Is undef a valid argument? by ikegami (Patriarch) on May 07, 2009 at 00:07 UTC
Like I already said, `$ARGV[0]` always evaluates to a scalar. As long as you keep using `$ARGV[0]`, you'll always get a scalar. If you want to pass zero when `@ARGV` is empty, you'll need to pass something different when `@ARGV` is empty. In general, you'd do `p1( @ARGV ? $ARGV[0] : () );` [download] In this case, the following suffices: `p1(@ARGV);` [download]	[reply] [d/l] [select]
Re^3: Question: Is undef a valid argument? by kennethk (Abbot) on May 06, 2009 at 22:01 UTC
You are still explicitly passing the first, non existent element of your array to your subroutine. If instead call your subroutine with `p1 @ARGV;` you will get your expected result.	[reply] [d/l]