What does $$ (dollar dollar or double dollar) mean in PHP?
Example is a variable declaration within a function:
global $$link;
What does $$ mean?
A syntax such as $$variable is called Variable Variable .
For example, if you consider this portion of code :
$real_variable = 'test';
$name = 'real_variable';
echo $$name;
You will get the following output :
test
Here :
$real_variable contains test $name contains the name of your variable : 'real_variable' $$name mean "the variable thas has its name contained in $name " $real_variable 'test' EDIT after @Jhonny's comment :
Doing a $$$ ?
Well, the best way to know is to try ;-)
So, let's try this portion of code :
$real_variable = 'test';
$name = 'real_variable';
$name_of_name = 'name';
echo $name_of_name . '<br />';
echo $$name_of_name . '<br />';
echo $$$name_of_name . '<br />';
And here's the output I get :
name
real_variable
test
So, I would say that, yes, you can do $$$ ;-)
The inner $ resolves the a variable to a string, and the outer one resolves a variable by that string.
So, consider this example
$inner = "foo";
$outer = "inner";
The variable:
$$outer
would equal the string "foo"
这是一个变量的变量。
<?php
$a = 'hello';
$$a = 'world'; // now makes $hello a variable that holds 'world'
echo "$a ${$a}"; // "hello world"
echo "$a $hello"; // "hello world"
?>
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