Question

I need to delete the first 29 values of an array. I searched and there doesn’t seem to be any built in PHP function that allows for this. How can this be done then?

Answer 1

You can use array_splice to remove values from an array:

array_splice($arr, 0, 29)

The array is passed as a reference as array_splice modifies the array itself. It returns an array of the values that have been removed.

Here’s an example for how it works:

$arr = range(1, 30);
$removed = array_splice($arr, 0, 29);
var_dump($arr);     // array(1) { [0]=> int(30) }
var_dump($removed); // array(29) { [0]=> int(1) … [28]=> int(29) }

In opposite to that, array_slice (without p) just copies a part of an array without modifying it:

$arr = range(1, 30);
$copied = array_slice($arr, 29);
var_dump($arr);    // array(30) { [0]=> int(1) … [29]=> int(30) }
var_dump($copied); // array(1) { [0]=> int(30) }

Here array_slice($arr, 29) copies everything from the offset 29 on up to the end while leaving the $arr as is.

But as you said you want to delete values, array_splice seems to be the better choice instead of copying a part and re-assigning the copied part back to the variable like this:

 $arr = array_slice($arr, 29);

Because although this has the same effect (first 29 values are no longer there), you do the copy operation twice: create a new array and copy everything except the first 29 values and then re-assign that value to $arr (requires copying the whole array again).