How to use Hash at PHP

Is there any way to declare a Hash like an Array at PHP, using a function like array()? I didn't find any function like hash() at PHP yet to declare a hash. But still I know how to make a hash, and use it.

Here is a small piece of code, that will show you how to make a hash. Print the value using key from the hash.

$hash['one'] = 1;
$hash['two'] = 2;
$hash['three'] = 3;

## inspect the variables using var_dump() function
var_dump($hash);

## print a single field from hash
print $hash['one'] . "\n";

You can also use foreach() loop to print all the key/values from the hash easily.

foreach($hash as $key=>$value){
    print "$key : $value\n";
}

But I'm still confused, whether it is a hash or an array? Anyone will take a hand to clarify this issue?