I don't see any loop, but I do see a couple of things which most likely don't do what you intended.  Maybe retry with this:

sub ddd {

    my $a = $_[0];
    my $b = $_[1];
    my $c = $_[2];
 
    # could also be written as:
    # my ($a, $b, $c) = @_;
    
    if ($a == 1) { $a = 'p'; }
    elsif ($a == 2) { $a = 'pp'; }
    
    if ($b == 3) { $b = 'w'}
    
    print "  < $a >  < $b > < $c >";
}
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