How to check if a string can be used as a variable name in PHP?

Question

In PHP one can use variable variables...

For example...

class obj { }
$fieldName = \"Surname\";
$object = new obj();
$object->Name = \"John\";
$objec         


        

Answer 1

However, `$fieldName string may contain some characters not allowed in variable names. PHP will still create the field with that name (much like the associative array), but I will not be able to access it with $object->...... because it would not parse correctly.

You will still be able to access the field through the $object->{"fieldname"} syntax.

As far as I know, the only restriction is that you can't access properties with \x00 in the name and you can't define variables starting with \x00.

Example:

$a = new stdclass;
$a->{"\x00dd"} = 8; //invalid
$a->{"dd\x00dd"} = 8; //valid, but...
echo $a->{"dd\x00dd"}; //can't read (no property "dd")