How to get a variable name as a string in PHP?

Question

Say i have this PHP code:

$FooBar = \"a string\";

i then need a function like this:

print_var_name($FooBar);

Answer 1

Lucas on PHP.net provided a reliable way to check if a variable exists. In his example, he iterates through a copy of the global variable array (or a scoped array) of variables, changes the value to a randomly generated value, and checks for the generated value in the copied array.

function variable_name( &$var, $scope=false, $prefix='UNIQUE', $suffix='VARIABLE' ){
    if($scope) {
        $vals = $scope;
    } else {
        $vals = $GLOBALS;
    }
    $old = $var;
    $var = $new = $prefix.rand().$suffix;
    $vname = FALSE;
    foreach($vals as $key => $val) {
        if($val === $new) $vname = $key;
    }
    $var = $old;
    return $vname;
}

Then try:

$a = 'asdf';
$b = 'asdf';
$c = FALSE;
$d = FALSE;

echo variable_name($a); // a
echo variable_name($b); // b
echo variable_name($c); // c
echo variable_name($d); // d

Be sure to check his post on PHP.net: http://php.net/manual/en/language.variables.php