Find the difference of two arrays and print bidirectional changes PHP -

i have 2 arrays:

$oldvalues = array(125 => 'hello', 126 => 'bye', 131 => 'hi', 141 => ''); $newvalues = array(125 => 'hello world', 126 => 'bye', 131 => 'h', 141 => 'abc'); 

now explain little better, $oldvalues holds values before user changes data on website. $newvalues holds new values after user has saved changes.

multiple users access page @ same time, if 1 user didnt refresh page , makes changes , clicks on save want able display "hey else has updated settings before did, wanna see changes?" , able see following output:

field        changed          changed 125          hello                 hello world 131          hi                    h 141                                abc 

note 126 not included since there no changes.

i have code using array_diff seems not work time.

$allpossiblefields = array(125, 126, 131, 141); $insertiondiff = array_diff($newvalues, $oldvalues); $deletiondiff  = array_diff($oldvalues, $newvalues);  $returnarray = array(); foreach($allpossiblefields $field) {   if (isset($insertiondiff[$field])) {       $returnarray[$field]['from'] = $oldvalues[$field];       $returnarray[$field]['to']   = $insertiondiff[$field];   }    if (isset($deletiondiff[$field])) {       if ( ! isset($returnarray[$field]['from']))       {          $returnarray[$field]['from'] = $deletiondiff[$field];       }        if ( ! isset($returnarray[$field]['to']))       {          $returnarray[$field]['to']   = $newvalues[$field];       }   } } 

but in cases returns empty array when there difference , in cases works. know there bug somewhere in here cant seem find it.

you can make lot simpler that;

foreach($oldvalues $key => $value) {     if($value != $newvalues[$key]) {         echo "field " . $key . " changed " . $value . " " . $newvalues[$key] . "<br />";     } }