How to add an array value to the middle of an associative array?

Question

Lets say I have this array:

$array = array(\'a\'=>1,\'z\'=>2,\'d\'=>4);

Later in the script, I want to add the value \'c\'=>3<

Answer 1

you can add it by doing

$array['c']=3;

and if you absolutely want it sorted for printing purposes, you can use php's ksort($array) function

if the keys are not sortable by ksort, then you will have to create your own sort by using php's uasort function. see examples here

http://php.net/manual/en/function.uasort.php

Answer 2

function insertValue($oldArray, $newKey, $newValue, $followingKey) {

    $newArray = array ();
    foreach (array_keys($oldArray) as $k) {
        if ($k == $followingKey)
            $newArray[$newKey] = $newValue;
        $newArray[$k] = $oldArray [$k];
    }

    return $newArray;
}

You call it as

insertValue($array, 'c', '3', 'z')

As for Edit 5:

edit your sql, so that it reads

SELECT ..., pizza, drink, pizza+drink as full_meal, ... FROM ....

and you have the column automatically:

Array (
  ...
  'pizza' => 12,
  'drink' => 5,
  'full_meal' => 17,
  ...
)

Answer 3

Associative arrays are not ordered, so you can simply add with $array['c'] = 3.

If order is important, one option is switch to a data structure more like:

$array = array(
   array('a' => 1),
   array('b' => 2)
   array('d' => 4)
);

Then, use array_splice($array, 2, 0, array('c' => 3)) to insert at position 2. See manual on array_splice.

Answer 4

According to your original question the best answer I can find is this:

$a = array('a'=>1,'z'=>2,'d'=>4);

$splitIndex = array_search('z', array_keys($a));
$b = array_merge(
        array_slice($a, 0, $splitIndex), 
        array('c' => 3), 
        array_slice($a, $splitIndex)
);

var_dump($b);
array(4) {
  ["a"]=>
  int(1)
  ["c"]=>
  int(3)
  ["z"]=>
  int(2)
  ["d"]=>
  int(4)
}

Depending on how big your arrays are you will duplicate quite some data in internal memory, regardless if you use this solution or another.

Furthermore your fifth edit seems to indicate that alternatively your SQL query could be improved. What you seem to want to do there would be something like this:

SELECT a, b, CONCAT(a, ' ', b) AS ab FROM ... WHERE ...

If changing your SELECT statement could make the PHP solution redundant, you should definitely go with the modified SQL.

Answer 5

Great usage of array functions but how about this as a simpler way:

Add a static column to the SQL and then replace it in the resultant array. Order stays the same:

SQL :

Select pizza , drink , 'pizza-drink' as 'pizza-drink' , 28 columns..... From Table

Array :

$result['pizza-drink'] = $result['pizza'] . $result['drink'];

Answer 6

function putarrayelement(&$array, $arrayobject, $elementposition, $value = null) {

        $count = 0;
        $return = array();
        foreach ($array as $k => $v) {
        if ($count == $elementposition) {
                if (!$value) {
                    $value = $count;
                }
            $return[$value] = $arrayobject;
            $inserted = true;
        }
        $return[$k] = $v;
        $count++;
        }
        if (!$value) {
           $value = $count;
        }
        if (!$inserted){
            $return[$value];
        }
        $array = $return;
       return $array;
     }

        $array = array('a' => 1, 'z' => 2, 'd' => 4);
        putarrayelement($array, '3', 1, 'c');
        print_r($array);