How to assign variable dynamically to php list function

Question

What I am doing that I want to generate a list based on how many items are in an array, so I have counted the items and loop over them, create a number based var and construct a string $var which contains $a1,$a2.... and assigns the $var to list list($var)

and tried to access $a1 but it gives me the error "Undefined variable: a1"

Is there any other way to do it?

Here is my code:

$arr = array('1','2','3');
$listsize = count($arr);
$var='';
for($i=1;$i<=$listsize;$i++){
        $var.='$a'.$i;
        if($i!=$listsize){
            $var.=',';
        }
}

list($var) = $arr;
echo $a1;

where is $a defined? you have just assigned its value to $var like this $var.='$a'.$i; — WatsMyName
– WatsMyName, Commented Sep 23, 2012 at 8:24
$a is just newly created var i am using that as string and producing the $a1 for use in list by above code echo $var will output as $a1,$a2,$a3 and using list($var) is my means by list($a1,$a2,$a3) = $arr and echo $a1 should be 1 is it clear — Ravi Soni
– Ravi Soni, Commented Sep 23, 2012 at 8:33

Burhan Khalid · Accepted Answer · 2012-09-24 04:07:35Z

1

What you are looking for is variable variables.

In PHP, you can dynamically assign variables names (not just values).

Here is an example:

$foo = "Hello" . 1;

# In this line, I am taking the value of the variable $foo (Hello1) and
# using that as as a variable name. This is equivalent to
# $Hello1 = "World", except the variable is dynamic (hence variable variables).

$$foo = "World";

print $Hello1; # This will print World

edited Sep 24, 2012 at 4:07

answered Sep 23, 2012 at 8:23

Burhan Khalid

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3 Comments

Ravi Soni Over a year ago

Hi Burhan this seems a considerable answer could you please include a example of using variable variables in this case.

Kev Over a year ago

Burhan - as per @ravisoni's comment it would be nice if you could expand your answer to provide a little more information.

Burhan Khalid Over a year ago

Actually the question is an exact duplicate; which is why I didn't expand on my answer. I will do so now.

egis · Accepted Answer · 2012-09-23 08:36:53Z

1

Why not use extract()?

Try this:

$values = array('1','2','3');
$variables = array();
$length = count($values);
$key = 'a1';

for ($i = 0; $i < $length; $i++){
  $variables[$key] = $values[$i];
  $key++;
}

extract($variables);
echo $a1, $a2, $a3;

answered Sep 23, 2012 at 8:36

egis

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Comments

Glavić · Accepted Answer · 2012-09-23 09:34:16Z

0

You can solve your problem without loops. Array $as is filled with your data, that has keys a1 to aX:

$arr = array('1', '2', '3', 'test', true, 4.56);
$keys = array_map(function($n) { return "a$n"; }, range(1, count($arr)) );
$a = array_combine($keys, $arr);

Array $as has keys and values like output bellow:

Array
(
    [a1] => 1
    [a2] => 2
    [a3] => 3
    [a4] => test
    [a5] => 1
    [a6] => 4.56
)

I advice you to use access to variables via array like $a['a3'], and not via variables like $a3.

If you would like to have $a1 ... $aX variables, extract array like:

extract($a);

answered Sep 23, 2012 at 9:34

Glavić

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