Hello adriang,

I realise your code snippet is just for illustration; still, it may be instructive to note its various problems:

1. while ( my $key=keys(%hash) {

   Compile error: the second closing parenthesis is missing.

2. my $key=keys(%hash)

   Logic error: in scalar context the keys function returns the number of keys in the hash, not the keys themselves. You need a for loop here:

   for my $key (keys %hash) {
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3. keys %hash

   Logic error: since you want to exit the loop when a certain key is reached, the behaviour of the code depends on the order in which the keys are returned; but this order is “apparently random” (keys). To get deterministic behaviour, you need to sort the keys. For example:

   for my $key (sort keys %hash) {
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4. }  $hash{$key}=$verb;

   Compile error: if you’re running under use strict; (and you should be!), you will see this error message:

   Global symbol "$key" requires explicit package name at ...
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   You could fix this¹ by declaring my $key; before the loop, but it’s better style to restrict the scope of this lexical variable:

   for my $key (sort keys %hash) {
       if ($key eq $verb) {
           $hash{$key} = $verb;
           last;
       }
   }
   [download]

Update (Aug 23):
¹That is, you could fix the error message. But the code still wouldn’t work correctly, because $key is a temporary alias within the foreach loop (see “alias” in perlglossary), and it reverts to its pre-loop value when the loop ends.

Hope that helps,