Question

I read php document and I saw this:

    class foo{
        var $bar = 'I am a bar';
    }

    $foo = new foo();
    $identity = 'bar';

    echo "{$foo->$identity}";

And I saw somebody wrote like this:

if (!isset($ns->job_{$this->id})){
   //do something
}

But when I tried with this code, It didn’t work:

$id1 = 10;

$no = 1;

echo ${id.$no};

Can you guys tell me why it didn’t work and when I can use braces with variable correctly?

Answer 1

Live example

Brackets can be used on object types, for instance, to simulate a array index. Supposing that $arr is an array type and $obj an object, we have:

$arr['index'] ===
$obj->{'index'}

You can make it more fun, for instance:

$arr["index{$id}"] ===
$obj->{"index{$id}"}

Even more:

$arr[count($list)] ===
$obj->{count($list)}

Edit: Your problem —
variable of variable

// Your problem
$id1 = 10;
$no = 1;
$full = "id{$no}";

var_dump($$full); // yeap! $$ instead of $