sub function1 {
    my $var = (defined $_[0]) ? $_[0] : "No argument";
    print $var . "\n";
}
[download]

sub function1 {
       my ($var) = @_? @_:'no arg';  
       print qq{$var\n};
}
function1(0);
function1('0');
function1('zero');
function1();
[download]

Output:
0
0
zero
no arg
[download]

Pass '0e0' instead of '0' when you want zero. It will evaluate true, but still act as zero for math.

#!/usr/bin/perl

use warnings;
use strict;

sub function1 {
    my $var = defined $_[0] ? shift : 'No argument';
    print "$var\n";
}

function1('zero');
function1(0);
function1('0');
function1(0e0);
function1('foolio');
function1();
[download]

Thank you all for your suggestions. Finally I used the following code to solve the problem:

sub function1
{
my $var = defined $_[0] ? shift : 'No argument';
print "$var\n";
}
[download]

But I still wonder if we cannot assign string value "0" to a variable using short circuit.

// works well, but that is in Perl 5.10.0. What if we have a situation like the following (in Perl 5.8.8), where we have multiple expressions involved in the short circuit in order of preference:

my $var = $hash1{$name} || $hash2{$name} || $some_default_value;
[download]

This will assign the default value to $var if say the key $name is not defined in %hash1 and is assigned a value 0 in %hash2. Is a if-elsif ladder or complex nested ternary operators the only way to solve this? Or may be this is the reason why they came up with // in Perl 5.10.0

Short circuit operators always evaluate in boolean context. In boolean context there are only true and false. The string "0" and numberic 0 are, among others, false. But, 0 (or empty string) is defined. So you need to check for defined-ness to allow them. See True or False? A Quick Reference Guide.

---

Open source softwares? Share and enjoy. Make profit from them if you can. Yet, share and enjoy!