Php array add key value pair to existing array

Question

Im trying to add a key=>value to a existing array with a specific value.

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Description
Return Values
How do I add a key to an existing array?
How do you add a key value pair to an array?
How do you create an array of key value pairs in PHP?
What is Array_keys () used for in PHP?

Im basically looping through a associative array and i want to add a key=>value foreach array that has a specific id:

ex:

[0] => Array
    (
        [id] => 1
        [blah] => value2

    )

[1] => Array
    (
        [id] => 1
        [blah] => value2
    )

I want to do it so that while

foreach ($array as $arr) {

     while $arr['id']==$some_id {

            $array['new_key'] .=$some value
            then do a array_push
      }    
}

so $some_value is going to be associated with the specific id.

Joseph Silber

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asked Jul 12, 2012 at 22:40

0

The while loop doesn't make sense since keys are unique in an associative array. Also, are you sure you want to modify the array while you are looping through it? That may cause problems. Try this:

$tmp = new array();
foreach ($array as $arr) {

     if($array['id']==$some_id) {
            $tmp['new_key'] = $some_value;
      }    
}


array_merge($array,$tmp);

A more efficient way is this:

if(in_array($some_id,$array){
  $array['new_key'] = $some_value;
}

or if its a key in the array you want to match and not the value...

if(array_key_exists($some_id,$array){
      $array['new_key'] = $some_value;
    }

answered Jul 12, 2012 at 22:46

TuckerTucker

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1

When you use:

foreach($array as $arr){
    ...
}

... the $arr variable is a local copy that is only scoped to that foreach. Anything you add to it will not affect the $array variable. However, if you call $arr by reference:

foreach($array as &$arr){ // notice the &
    ...
}

... now if you add a new key to that array it will affect the $array through which you are looping.

I hope I understood your question correctly.

answered Jun 24, 2013 at 20:59

Php array add key value pair to existing array

If i understood you correctly, this will be the solution:

foreach ($array as $arr) {
  if ($arr['id'] == $some_id) {
     $arr[] = $some value;
     // or: $arr['key'] but when 'key' already exists it will be overwritten
  }
}

answered Jul 12, 2012 at 22:46

BesnikBesnik

6,3031 gold badge30 silver badges32 bronze badges

(PHP 4, PHP 5, PHP 7, PHP 8)

array_push — Push one or more elements onto the end of array

Description

array_push(array &$array, mixed ...$values): int

repeated for each passed value.

Note: If you use array_push() to add one element to the array, it's better to use $array[] = because in that way there is no overhead of calling a function.

Note: array_push() will raise a warning if the first argument is not an array. This differed from the $var[] behaviour where a new array was created, prior to PHP 7.1.0.

Parameters

array

The input array.

values

The values to push onto the end of the array.

Return Values

Returns the new number of elements in the array.

Changelog

Version	Description
7.3.0	This function can now be called with only one parameter. Formerly, at least two parameters have been required.

Examples

Example #1 array_push() example

$stack = array("orange", "banana"); array_push($stack, "apple", "raspberry"); print_r($stack); ?>

The above example will output:

Array
(
    [0] => orange
    [1] => banana
    [2] => apple
    [3] => raspberry
)

I can only assume that PHP sorts the array as elements are added to make it easier for it to find a specified element by its key later. In many cases it won't matter if the array is not stored internally in the same order you added the elements, but if, for instance, you execute a foreach on the array later, the elements may not be processed in the order you need them to be.

If you want to add elements to the END of an associative array you should use the unary array union operator (+=) instead...

$data['one'] = 1; $data += [ "two" => 2 ]; $data += [ "three" => 3 ]; $data += [ "four" => 4 ];

You can also, of course, append more than one element at once...

$data['one'] = 1; $data += [ "two" => 2, "three" => 3 ]; $data += [ "four" => 4 ];

Note that like array_push (but unlike $array[] =) the array must exist before the unary union, which means that if you are building an array in a loop you need to declare an empty array first...

$data = []; for ( $i = 1; $i < 5; $i++ ) { $data += [ "element$i" => $i ]; }

...which will result in an array that looks like this...

[ "element1" => 1, "element2" => 2, "element3" => 3, "element4" => 4 ]

raat1979 at gmail dot com ¶

6 years ago

Unfortunately array_push returns the new number of items in the array It does not give you the key of the item you just added, in numeric arrays you could do -1, you do however need to be sure that no associative key exists as that would break the assumption

It would have been better if array_push would have returned the key of the item just added like the below function (perhaps a native variant would be a good idea...)

if(!function_exists('array_add')){ function array_add(array &$array,$value /*[, $...]*/){ $values = func_get_args(); //get all values $values[0]= &$array; //REFERENCE! $org=key($array); //where are we? call_user_func_array('array_push',$values); end($array); // move to the last item $key = key($array); //get the key of the last item if($org===null){ //was at eof, added something, move to it return $key; }elseif($org<(count($array)/2)){ //somewhere in the middle +/- is fine reset($array); while (key($array) !== $org) next($List); }else{ while (key($array) !== $org) prev($List); } return $key; } } echo "