Illegal Offset error in php array

Question

I have an array that looks like this, that I'm looping through: Name of Array is $test

Array
(
[ven1] => Array
    (
        [0] => Array
            (
                [0] => ven1-center1
                [1] => ven1
                [2] => Address
            )

        [1] => Array
            (
                [0] => ven1-center2
                [1] => ven1
                [2] => Address
            )

        [2] => Array
            (
                [0] => ven1-center3
                [1] => ven1
                [2] => Address
            )

           .
           .
           .


 [ven2] => Array
    (
        [20] => Array
            (
                [0] => ven2-center1
                [1] => ven2
                [2] => Address
            )

        [21] => Array
            (
                [0] => ven2-center2
                [1] => ven2
                [2] => Address
            )

        [22] => Array
            (
                [0] => ven2-center3
                [1] => ven2
                [2] => Address
            )

I have the php code below to loop the whole array, grab all the values of [0] from the innermost dimension, store them into an array with the name of $k. When I run the code below, I get Notice: Undefined offset: for all the values of $c.

    for($c = 0; $c < 42; $c++){
        foreach($test as $k =>  $v){
          if($test[$k][$c][1] == $k){
           $k = $test[$k][$c][0];
         }
       }
     }

The output am looking for is

$ven1 = array("ven1-center1","ven1-center2","ven1-center3","ven1-center4")
$ven2 = array("ven1-center1","ven1-center2","ven1-center3","ven1-center4")

Creating numbered variables like that is almost always wrong. Use an array. — Barmar
– Barmar, Commented Jun 13, 2014 at 0:31
Instead of $ven1 and $ven2, you should have an array $ven, with $ven['ven1'] = array("ven1-center1","ven1-center2","ven1-center3","ven1-center4") and $ven['ven2'] = array("ven1-center1","ven1-center2","ven1-center3","ven1-center4"). — Barmar
– Barmar, Commented Jun 13, 2014 at 0:37

dave · Accepted Answer · 2014-06-13 00:19:07Z

1

I think this will do what you want... assuming I interpreted your question correctly:

foreach($test as $varname => $array){
   foreach($array as $row) {
       if ($row[1] == $varname) ${$varname}[] = $row[0];
   }
}

var_dump($ven1);
var_dump($ven2);

answered Jun 13, 2014 at 0:19

dave

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3 Comments

hello Over a year ago

Both $ven1 and $ven2 echoes out exactly. When I print_r( ${$varname}) I do not get an array of $ven1 and $ven2. Is this normal? Also can what notation is ` ${$varname}` ? Thanks

Barmar Over a year ago

It's called a variable variable. us3.php.net//manual/en/language.variables.variable.php

dave Over a year ago

${$varname}[] means take the variable with name $varname - so in this case, $varname contains "ven1", so we are taking the variable $ven1. Normally you can do $$varname, but since it's an array, we have to use {} because it's ambiguous if the [] refers to $varname or $$varname.

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