Hi Monks,

Today I wrote a small script for my friend to check the sum of the digits recursively (till single digit of length), numbers range from 1500 to 2300. For example:

Number 1818
1818 = 1+8+1+8 = 36   step 1 (2 digits output)
36   = 3 + 6 = 9      step 2 (single digit output)
result: 9 (final count of the digits )
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I wrote the below code and found the final total is printing continuously. I expected only 9 but it is printing both 9 and 18 continuously. I solved the issue later (case 2). But I want to know the reason why it is printing continuously 9 and 18. Because of that I am not getting final output '1818 == 9' in the main program.

I 'super searched' in perlmonks and found following links. subroutine recursion question,Recursion problem, Recursion. But I was not able to find correct answer. Even I googled but I didn't get correct answer. Even I flushed using $| but not able to get expected output. Where am I going wrong? Could someone explain where I am making mistake?

use strict;
use warnings;

my $total1;

for my $num (1818..1818){   
     
     my $total1 = &spl($num);             
     
     print "$num == 9\n" if ($total1 == 9);
     
}

################# not working as i expected ####### case 1

sub spl{
    
my ($num1) = @_;    

my $total = 0;

$total = $total + $_ for (split '', $num1);

print "total: $total\n";

my $len = length ($total);

print "length: $len\n";

&spl($total) if ($len != 1);

print "final: $total\n";

return $total;

}


########## working perfectly #########   case 2

#sub spl{
#    
#my ($num1) =@_;    
#
#my $total = 0;
#
#$total = $total + $_ for (split '', $num1);
#
#my $len = length ($total);
#
#return $total if ($len == 1);
#
#&spl($total) if ($len != 1);
#
#}


output:
-------
total: 18
length: 2
total: 9
length: 1
final: 9
final: 18

Expected output:
----------------
total: 18
length: 2
total: 9
length: 1
final: 9
1818 == 9
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