Add a prefix to each item of a PHP array

Question

I have a PHP array of numbers, which I would like to prefix with a minus (-). I think through the use of explode and implode it would be possible but my knowledge of php is not possible to actually do it. Any help would be appreciated.

Essentially I would like to go from this:

$array = [1, 2, 3, 4, 5]; 

to this:

$array = [-1, -2, -3, -4, -5]; 

Any ideas?

Answer 1

An elegant way to prefix array values (PHP 5.3+):

$prefixed_array = preg_filter('/^/', 'prefix_', $array); 

Additionally, this is more than three times faster than a foreach.

Answer 2

Simple:

foreach ($array as &$value) {    $value *= (-1); } unset($value); 

Unless the array is a string:

foreach ($array as &$value) {     $value = '-' . $value; } unset($value);