PHP foreach: replace value in nested array

Question

I want to change 'value2' to 'My string'. I know this is possible by using the array keys but I wonder if it's a cleaner way.

$nested_array[] = array('value1', 'value2', 'value3');

foreach($nested_array as $values){

    foreach($values as $value){

        if($value == 'value2'){
            $value = 'My string';
        }

    }

}

Answer 1

Just use the reference operator &to pass values by reference:

foreach($nested_array as &$values) {
    foreach($values as &$value) {
        do_something($value);
    }
}
unset($values); // These two lines are completely optional, especially when using the loop inside a
unset($value);  // small/closed function, but this avoids accidently modifying elements later on.

Answer 2

You could also use array_walk_recursive for this:

array_walk_recursive($nested_array,
                     function(&$v) {
                         if ($v == 'value2') $v = 'My string';
                     }
);

This would work for any level of nesting and you don't need to remember to unset anything afterwards.

Answer 3

The PHP function array_search is what you 're searching for.

$key = array_search('value2', $nested_array);
$nested_array[$key] = 'My String';

This solution would be more performant than iterating through the whole array.

Answer 4

By using array keys:

$nested_array = array();
$nested_array[] = array('value1', 'value2', 'value3');

foreach($nested_array as $key => $values){

    foreach($values as $key2 => $value){

        if($value == 'value2'){
            $nested_array[$key][$key2] = 'My string';
        }
    }
}
var_export($nested_array);
// array ( 0 => array ( 0 => 'value1', 1 => 'My string', 2 => 'value3', ), )

Answer 5

function strReplaceAssoc(array $replace, $subject) { 
   return str_replace(array_keys($replace), array_values($replace), $subject);    
}

$nested_array[] = array('value1', 'value2', 'value3');

foreach($nested_array as $values){

    foreach($values as $value){

        $replace = array( 
            'value2' => 'My string' 
            );

        $new_values = strReplaceAssoc($replace,$value);

       echo $new_values . '<br />';

    }

}