Question

Can anyone tell me why this works (it echos out “poo”):

$input = "wee";
$val = "poo";
${$input} = $val;
echo $wee;

But this doesn’t:

function bodily($input) {
    $val = "poo";
    ${$input} = $val;
}
bodily("wee");
echo $wee;

I want to use this sort of method to play with some $_POST vars. Please tell me if I can explain more… Cheers!

Answer 1

Your variable $wee gets only defined inside the scope of your function bodily(). It is not defined outside this function.

You could make it global, anyway this is not a useful pattern for a real life application:

function bodily($input) {
    $val = "poo";
    global ${$input}; // make your $wee defined in the global scope
    ${$input} = $val;
}
bodily("wee");
echo $wee;

outputs

poo