View Full Version : [SOLVED] Perl wantarray

November 13th, 2008, 07:03 PM
does anyone know what does wantarray function in perl does? i looked it up in here (http://perldoc.perl.org/functions/wantarray.html).

below is its contents:

Returns true if the context of the currently executing subroutine or eval is looking for a list value. Returns false if the context is looking for a scalar. Returns the undefined value if the context is looking for no value (void context).

return unless defined wantarray; # don't bother doing more
my @a = complex_calculation();
return wantarray ? @a : "@a";

wantarray()'s result is unspecified in the top level of a file, in a BEGIN , UNITCHECK , CHECK , INIT or END block, or in a DESTROY method.

This function should have been named wantlist() instead.

i can't understand what it is trying to say. what is meant by context, void context and non-void context?

i tried the following code but i always get the same result - error

use warnings;
use strict;
&my_sub("something", "something");

sub my_sub {
if (defined wantarray) {
print "wantarray\n";
} else {
print "error\n";

Also does anyone know any dedicated perl forums for newbies and perl gurus wanna be?


November 13th, 2008, 07:53 PM
wantarray is a magic token that is defined within each function. It is true when the function was called in an array context, and it is false when the function is called in a scalar context.

Here is an example:

use strict;
use warnings;
my $result;
my @result;

$result=&my_sub("something", "something");
print "my_sub returns scalar:\n$result\n";

print "-"x80,"\n";
@result=&my_sub("something", "something");
print "my_sub returns array:\n";
foreach $result (@result) {
print "$result\n"

sub my_sub {
my @data=@_;
if (wantarray) {
return @data;
} else {
my $data=join('+',@data);
return $data;


my_sub returns scalar:
my_sub returns array:

Here is a dedicated perl forum: http://perlmonks.org/
If you google "perl forum" you will find many others too.

November 13th, 2008, 08:00 PM
Hey there,

Check out the side bar of the url you posted. You'll find these:

<li><a href="http://search.cpan.org">CPAN</a></li>
<li><a href="http://www.perl.org">Perl.org</a></li>
<li><a href="http://www.perl.com">Perl.com</a></li>
<li><a href="http://perlbuzz.com">Perl Buzz</a></li>
<li><a href="http://www.perlfoundation.org/perl5/index.cgi">Perl 5 Wiki</a></li>
<li><a href="http://jobs.perl.org">Perl Jobs</a></li>
<li><a href="http://www.pm.org">Perl Mongers</a></li>
<li><a href="http://www.perlmonks.org">Perl Monks</a></li>
<li><a href="http://planet.perl.org">Planet Perl</a></li>
<li><a href="http://use.perl.org">Use Perl</a></li>

For what it is worth, I always learn something new whenever I visit Perl Monks.