PHP - Variable inside variable?

Question

$bookA = \"123\"; $crack = \"A\";

I want to do something similar to this:

echo $book$crack;

Such that the output is 123

Answer 1

You might want to use an associative array.

For instance:

$book = array();
$book["A"] = "Some Book";
$crack = "A";

//Later
echo $book[$crack];