I just want to use array_walk() with ceil() to round all the elements within an array. But it doesn't work.
The code:
$numbs = array(3, 5.5, -10.5);
array_walk($numbs, "ceil");
print_r($numbs);
output should be: 3,6,-10
The error message:
Warning: ceil() expects exactly 1 parameter, 2 given on line 2
output is: 3,5.5,-10.5 (Same as before using ceil())
I also tried with round().
Use array_map instead.
$numbs = array(3, 5.5, -10.5);
$numbs = array_map("ceil", $numbs);
print_r($numbs);
array_walk actually passes 2 parameters to the callback, and some built-in functions don't like being called with too many parameters (there's a note about this on the docs page for array_walk). This is just a Warning though, it's not an error.
array_walk also requires that the first parameter of the callback be a reference if you want it to modify the array. So, ceil() was still being called for each element, but since it didn't take the value as a reference, it didn't update the array.
array_map is better for this situation.
array_* function is better than another, depending on the situation.I had the same problem with another PHP function. You can create "your own ceil function". In that case it is very easy to solve:
function myCeil(&$list){
$list = ceil($list);
}
$numbs = [3, 5.5, -10.5];
array_walk($numbs, "myCeil");
// $numbs output
Array
(
[0] => 3
[1] => 6
[2] => -10
)
The reason it doesn't work is because ceil($param) expects only one parameter instead of two.
What you can do:
$numbs = array(3, 5.5, -10.5);
array_walk($numbs, function($item) {
echo ceil($item);
});
If you want to save these values then go ahead and use array_map which returns an array.
UPDATE
I suggest to read this answer on stackoverflow which explains very well the differences between array_map, array_walk, and array_filter
Hope this helps.
array_walk will call your callback function and pass it 2 parameters ($value and $key). The array wasn't getting updated because array_walk will only do that if the $value parameter is a reference (and its value is updated in the callback).That is because array_walk needs function which first parameter is a reference &
function myCeil(&$value){
$value = ceil($value);
}
$numbs = array(3, 5.5, -10.5);
array_walk($numbs, "myCeil");
print_r($numbs);
