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?
2 Answers
array_splice($array, 0, 29);
array_splice deletes the elements from the array and returns the deleted elements.
Alternatively, if you want to keep the original array, but want to create a new array with the first 29 elements removed, use array_slice:
$newArray = array_slice($array, 29);
2 Comments
Sammy
This leaves me with the first 29 values, I want instead to remove the first 29 and be left with the rest.
NikiC
@Sammy: Are you sure you used array_splice? And are you sure you didn't assign the value (like
$array = array_splice($array, 0, 29), that would be wrong. You should not assign the value!)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).
5 Comments
Sammy
This leaves me with the first 29 values, I want instead to remove the first 29 and be left with the rest.
Gumbo
@Sammy: As already said,
array_splice modifies the passed array and only returns the values that have been removed.Sammy
ahhhh I didn't know it actually modifies the original array. I was able to achieve what I wanted by doing the array splice and not really using the returned value but instead calling on the original which after the splice had the first 29 values removed.
Gumbo
@Sammy: You should read more carefully instead of just copying the code. ;)
Sammy
I just saw your edits when I refreshed the page after 10 minutes, before they weren't there.
unset: php.net/manual/en/function.unset.php