PHP 忒聊 綴豖 梒 8. 曹講 ヶ輛 褫曹曹講 Sometimes it is convenient to be able to have variable variable names. That is, a variable name which can be set and used dynamically. A normal variable is set with a statement such as: ?php $a = "hello";? A variable variable takes the value of a variable and treats that as the name of a variable. In the above example, hello, can be used as the name of a variable by using two dollar signs. i.e. ?php $$a = "world";? At this point two variables have been defined and stored in the PHP symbol tree: $a with contents "hello" and $hello with contents "world". Therefore, this statement: ?php echo "$a ${$a}";? produces the exact same output as: ?php echo "$a $hello";? i.e. they both produce: hello world. In order to use variable variables with arrays, you have to resolve an ambiguity problem. That is, if you write $$a[1] then the parser needs to know if you meant to use $a[1] as a variable, or if you wanted $$a as the variable and then the [1] index from that variable. The syntax for resolving this ambiguity is: ${$a[1]} for the first case and ${$a}[1] for the second. Please note that variable variables cannot be used with PHP's Superglobal arrays. This means you cannot do things like ${$_GET}. If you are looking for a way to handle availability of superglobals and the old HTTP_*_VARS, you might want to try referencing them. 綴豖 れ萸 ヶ輛 曹講毓峓 奻珨撰 PHP 腔俋窒曹講