Dynamically change a variables name

[jc_gmk]

Is it possible to change the name of the variable dynamically

e.g.

I want to set these variables on a page:

$id1 = $_GET['id1'];
$id2 = $_GET['id2'];
$id3 = $_GET['id3'];
$id4 = $_GET['id4'];
etc... 

only I don't know how many of these I will have on the page as the number will be generated from the previous page. could be 4 or 100.

I think i need some kind of loop such as

for ($i=1; $i<=$qty; $i++)
{
$id* = $_GET['id*'];
} 

I want to change $id* to $id1, $id2 ,$id3, $id4 etc...
depending on the value of $qty

does anyone know if this is even possible? Or if i'm making any sense!

[boogyman]

for ($i=1; $i<=$qty; $i++)
{
$id.$i = $_GET['id'.$i];
} 

[jc_gmk]

Sweet! easy as that.

Thanks!

[djr33]

Ah, I wasn't aware that was valid syntax. Thanks for that, boogyman.

The method I have always used is "variable variables", like this:

$$name = 1;

So....
$name = 'test';
$$name = 1;
echo $test; //1

If you need to have a more complex variable name, you'll just need to create it in the previous line:

$name = $a.'b'.$c.'abc';
$$name; //use as you want


Though $a.$b may work, be cautious when modifying that syntax as some forms do not work. $$var will always work, and refer to the variable named the value of $var.

[boogyman]

Ah, I wasn't aware that was valid syntax. Thanks for that, boogyman.

The method I have always used is "variable variables", like this:

$$name = 1;

So....
$name = 'test';
$$name = 1;
echo $test; //1

If you need to have a more complex variable name, you'll just need to create it in the previous line:

$name = $a.'b'.$c.'abc';
$$name; //use as you want


Though $a.$b may work, be cautious when modifying that syntax as some forms do not work. $$var will always work, and refer to the variable named the value of $var.

I have never had any problems with doing it that way. Whether its technically valid or not you would probably have to refer to either guru that is Twey / John.
I can understand your method of assigning the variable by reference, but personally concantenating the variables are easily for me.. well at least in this instance. Its really no different than if you were doing

for($i=0; $i<max; $i++)
{
      $var[$i] = something;
}

[Twey]

$id.$i = $_GET['id'.$i];

This will not work, at least in PHP5. Instead, it will be interpreted as $id . ($i = $_GET['id' . $i]). djr33's method is the correct one, but any use of variable variables is almost certainly an indicator of bad code. The simplest way of accomplishing what you want is:

foreach($_GET as $k => $v)
  if(strpos($k, 'id') === 0)
    $$k = $v;

However, I would strongly suggest:

• Not doing this; this style of coding
  • opens up several security risks for which you must plan if you intend to use it;
  • clutters up the global namespace;
  • will not allow autoglobal access to these variables inside functions, so you'd have to do

    function foo() {
      global $id1;
      global $id2;
      global $id3;
      global $id4;
    }

    ... or equivalent inside your functions.
  If you find $_GET['id4'] too much to type, you can always copy $_GET to another variable:

  $g = $_GET;

• Using an array for these values; according to the CGI specification simply having multiple elements in your form with the same name should be enough to cause the value to be an array as handled in your server-side script, but PHP is somewhat broken in respect to this specification, and therefore when passing values to it in an array you must end the names with []:

  <input type="text" name="ids[]">
  <input type="text" name="ids[]">
  <input type="text" name="ids[]">
  <!-- ... -->

  $_GET['ids'] will then be an array containing all these values, which you can manipulate using normal array functions.

Whether its technically valid or not you would probably have to refer to either guru that is Twey / John.

As far as I'm aware, John knows no PHP. I envy him this somewhat

Its really no different than if you were doing [an array assignment]

It is very different, primarily in that the syntax is ambiguous (and apparently differs between versions) and also in that it relies upon a deprecated feature, namely the interpretation of id as a string rather than an undefined constant, to work.

[jc_gmk]

Using an array for these values; according to the CGI specification simply having multiple elements in your form with the same name should be enough to cause the value to be an array as handled in your server-side script, but PHP is somewhat broken in respect to this specification, and therefore when passing values to it in an array you must end the names with []:

<input type="text" name="ids[]">
<input type="text" name="ids[]">
<input type="text" name="ids[]">
<!-- ... -->

$_GET['ids'] will then be an array containing all these values

This was exactly what i was looking to do, thanks!
Looked as though I was trying to do it the hard way!

Following on from that though, I have now collected two differant arrays using this method

e.g.
$id = array( [0] => 100 [1] => 221 [2] => 343 );
and
$qty = array( [0] => 3 [1] => 6 [2] => 1 );

Am i able to merge them?
I need to end up with an array like this:

$cart = array(100,100,100,221,221,221,221,221,221,343);

Notice that the first value "100" matches up with the "3" and prints "100,100,100" and "221" to the "6" and so on...

[Twey]

$cart = array();
foreach($id as $k => $v)
  for($i = 0; $i < $qty[$k]; ++$i)
    $cart[] = $v;

[djr33]

There are also simple functions, like array_merge(), but I'm not sure that's customizable enough for your current purposes.

[jc_gmk]

No luck, if the first value of $id is "100" and $qty is "6" it just prints out this array:

Array ( [0] => 600 [1] => 0 [2] => 0 [3...

i would need it to look like this:

Array ('100','100','100','100','100','100')