Retrieve first key in multi-dimensional array using PHP

There are other ways of doing it but nothing as quick and as short as using key(). Every other usage is for getting all keys. For example, all of these will return the first key in an array:

$keys=array_keys($this->data);
echo $keys[0]; //prints first key

foreach ($this->data as $key => $value)
{
    echo $key;
    break;
}

As you can see both are sloppy.

If you want a oneliner, but you want to protect yourself from accidentally getting the wrong key if the iterator is not on the first element, try this:

reset($this->data);

reset():

reset() rewinds array 's internal pointer to the first element and returns the value of the first array element.

But what you're doing looks fine to me. There is a function that does exactly what you want in one line; what else could you want?