This is an abuse of the ternary operator.

Normally in this situation, you want to choose between 3 choices, not two!

Use the ternary operator to set a variable dependent upon a true/ false condition.
A common use would be like this:
($today eq 'Monday') ? $firstDay =1 : $firstDay =0;

That would be preferred over:
$firstDay=0;
$firstDay=1 if ($today eq 'Monday');

Use if and if/elsif/else conditions for more complicated things.

#!/usr/bin/perl -w
use strict;

decide ('add');
decide ('edit');
decide ('bad input nothing');

print "\n";

decide2 ('add');
decide2 ('edit');
decide2 ('bad input nothing');


sub decide
{
   my $input = shift;
   
   print "invalid input\n" if ($input ne "add" and $input ne "edit");
   print "doing an add\n"  if $input eq "add";
   print "doing an edit\n" if $input eq "edit";
}

sub decide2
{
   my $input = shift;
   if ($input eq 'add')
   {
      print "the add code goes here\n";
   }
   elsif ($input eq 'edit')
   {
      print "the edit code goes here\n";
   }
   else
   {
      print "the invalid input code goes here\n";
   }
}

__END__
doing an add
doing an edit
invalid input

the add code goes here
the edit code goes here
the invalid input code goes here
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