$ and % operator being used in conjunction

Question

I'm busy learning Perl at the moment and I've been given some code to look at and "solve". ``` foreach $field (keys %$exam) ``` The code above is the area Im having difficulty in understanding. I thought $ was scalar and % was a hash and so I'm unsure what %$ is. Any help appreciated! Thanks guys.

Accepted Answer

```
$exam = {a=>1, b=>2}; # anonym hash, $exam is ref for this hash
```

In order to use this ref like hash you have to use dereferencing operator `%` before ref

`foreach $field (keys %$exam)`

For example the same for array ref.

```
$a = [1,2,3,4]; # anonym arr, $a is ref for this array
```

So that you have to use operator `@` before ref $a for dereferencing

`foreach $element (@$a) {print $element;}`

$ and % operator being used in conjunction

Solution

Problem