An alternative to the other suggestions is to use (s)printf:

my $str = 'params.%d.arg';
                                                                      
+          
for my $idx (0 .. 9 )
{
   printf $str, $idx;
}
[download]

You will need to be careful in sanitizing the contents of $str if all or part of it is being taken from user (or otherwise untrusted) input .

/J\