Checking for an undefined array 1

[rvBasic]

The following subroutine (pseudo code) can return an array or undef depending on validity checking of the input parameters;

sub rout{
my @Ar = $_[0]=~m/([\+-])?\s*([\d:]+),(\d{3}$)/;
#Some processing follows that results in either
# if valid parameters:
return (@Ar);
# or (if invalid)
return (undef);
}

But whatever I try in the main program the following test ALWAYS results as if the array was defined.

my $Br=();
@Br=&rout($SomeParm);
if (@Br){print "DEFINED\n";}
else {print "NOT DEFINED\n";}

if I replace the if (@Br) by if (defined(@Br)) then Perl is not happy and produces a message telling that defined has been depreciated.
However the following code does produce the desired result:

if (&rout($SomeParm)){@Br=&rout($SomeParm);print "DEFINED\n";}
else {print "NOT DEFINED\n";}

but at the expense if executing the sub twice.
How can I get what I want with one execution of the subroutine?

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In theory, there is no difference between theory and practice. In practice, there is. [attributed to Yogi Berra]

 

[prex1]

Just say [tt]return;[/tt] instead of [tt]return(undef);[/tt] for the invalid condition.
An array containing one [tt]undef[/tt] element is defined.

Franco

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

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http://www.levitans.com

: Air bearing pads

 

[rvBasic]

Yes, indeed. Thanks prex1, the star is yours!

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In theory, there is no difference between theory and practice. In practice, there is. [attributed to Yogi Berra]