Check for differnent values between new and old arrays PHP - php

Question

I have an array of values that will get updated periodically. When the array is updated, I want to perform an action using the new values in the updated array.
$old_node->field_name[0]['value'] = 'red'
$old_node->field_name[1]['value'] = 'yellow'
$old_node->field_name[2]['value'] = 'blue'
$updated_node->field_name[0]['value'] = 'green',
$updated_node->field_name[1]['value'] = 'red',
$updated_node->field_name[2]['value'] ='purple',
$updated_node->field_name[3]['value'] = 'blue',
So the values of 'green' and 'purple' are the new values in the new array. I need to run each of the values that are ADDED to the new array through a function. Something like:
foreach(of the newly added values that are in the new array){
//do stuff;
}
Some values may be deleted when the array is updated, so the the key=>value pairs could change.
I've tried:
foreach($updated_node->field_name as $new_value){
if(!in_array($new_value['value'], $old_node->field_name) && $new_value['value'] !== NULL){
//Do stuff;
}
}
But that doesn't work. I've also tried picking out new values with array_diff and array_intersect, but that's not working either.

Answer 1

use array_diff()
$old_array = array(
0 => 'red',
1 =>'yellow',
2 => 'blue'
);
$new_array = array(
0 => 'green',
1 => 'red',
2 =>'purple',
4 => 'blue'
);
$diff = array_diff($new_array, $old_array);
print_r($diff);
/*
Array
(
[0] => green
[2] => purple
)
*/
for your new code
$old_node->field_name[0]['value'] = 'red';
$old_node->field_name[1]['value'] = 'yellow';
$old_node->field_name[2]['value'] = 'blue';
$updated_node->field_name[0]['value'] = 'green';
$updated_node->field_name[1]['value'] = 'red';
$updated_node->field_name[2]['value'] = 'purple';
$updated_node->field_name[3]['value'] = 'blue';
$diff = array();
foreach($updated_node->field_name as $num => $field){
$tmpval = false;
foreach($old_node->field_name as $old){
if($field['value'] == $old['value']){
$tmpval = true;
}
}
if(!$tmpval){
$diff[$num] = $field['value'];
}
}
print_r($diff);
/*
Array
(
[0] => green
[2] => purple
)
*/

Answer 2

$old_array = array(
[0] => 'red',
[1] =>'yellow',
[2] => 'blue',
);
$new_array = array(
[0] => 'green',
[1] => 'red',
[2] =>'purple',
[4] => 'blue',
);
$diff = array_diff($new_array, $old_array);
var_dump($diff);
That results in
array(2) {
[0]=>
string(5) "green"
[2]=>
string(6) "purple"
}
which is the correct (expected) result.

Answer 3

Here is a simple function to load up two arrays with the added and removed values:
function loadArrayDifferences($before, $after, &$added, &$removed) {
$added = array_diff($after, $before);
$removed = array_diff($before, $after);
}
and here is a test script:
<?php
$ar1 = array(
'one',
'two',
'three',
'four'
);
$ar2 = array(
'two',
'four',
'six',
'eight',
);
$adds = array();
$rems = array();
loadArrayDifferences($ar1, $ar2, $adds, $rems);
var_dump($adds);
var_dump($rems);
function loadArrayDifferences($before, $after, &$added, &$removed) {
$added = array_diff($after, $before);
$removed = array_diff($before, $after);
}
which outputs:
array(2) {
[2]=>
string(3) "six"
[3]=>
string(5) "eight"
}
array(2) {
[0]=>
string(3) "one"
[2]=>
string(5) "three"
}