Quite possibly one of PHP’s least utilized yet most valuable features is its support for Variable Variables. In short these are a method of using the value of one variable to call the name of another. Sound confusing? We'll explain everything...
A variable variable is, in short, a method of using the value of one variable to call the name of another. For instance, if I had a variable $x with the value of "Eric", I could set a variable $Eric to "Seufert" by simply writing $$x = "Seufert". This process calls the value of $x and then creates a variable out of it. Therefore,
echo "$x ${$x}";
would produce the same output as,
echo "$x $Eric";
which is:
Eric Seufert
Notice the curly braces around the variable variable in
the first echo statement. This is the standard syntax for outputting variable variables. Omitting the curly braces would have resulted with the following output:
/ 15 
