in reply to
Calculating a persons age based on their birthday.

As far as I understand, you would like to know the number of full years the person is alive?

So, assuming you have only the number of day, we can do the following:

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my $year = (localtime)[5]+1900;

my $fullyears=0;

$nod = xxxx; #number of days goes here...

while ($nod > 365)

{ if ( $year % 4) {$nod=$nod-365} else {$nod=$nod-366}; #check for the leap year.

$year--; $fullyears++;

};

print "$fullyears\n";

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Rather simple but m.b. not so gracefull solution :) You see, you do not need any special modules.