What does $$ in php mean?

 

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  • What does $$ (dollar dollar or double dollar) mean in PHP? 6 answers

    • In PHP, $$ means you are about to inflict years of pain and suffering on at least one maintenance programmer. Note that you might wind up being that maintenance programmer.

    It is a variable variable. Imagine this: 

    $quux = 'bar';
$foo[$quux] = "baz";
echo $foo['bar']; //prints baz

    if there was no such thing as arrays, you might try something like this: 

    $quux = 'bar';
$$quux = "baz";
echo $bar; //prints baz

    luckily we do have arrays so please don't use variable variables unless you are doing something convoluted and magical * and have no other choice.

    * : Please don't do convoluted magical things, either.

    这些被称为变量变量。 

    $foo = 'bar';
$id = 'foo';

echo $id;  // prints foo
echo $$id; // prints bar

    in the PHP manual of course

    http://www.php.net/manual/en/language.variables.variable.php

    note that it's obsolete and senseless syntax and you should always use arrays instead.

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