Remove element from array, not using unset()

Question

If I use unset() I get error: Undefined offset: on index I deleted. How could I remove this appropriately ?

PHP:

<pre>
<?php

$a = array("foo", "baa", "ahahaha");

unset($a[1]);
//echo '<pre>'; print_r($a);

for($i = 0; $i < count($a); $i++) {
    echo 'val at ', $i;
    echo " ", $a[$i], "\r\n";
}

?>

error:

Notice: Undefined offset: 1 in file.php

I think you can find what you're looking for here: http://stackoverflow.com/questions/369602/delete-an-element-from-an-array — Luuuud, Jun 06 '14 at 15:45
Its all correct behaviour. You unset $a[1]. And afterwards you are trying to echo $a[1] because of the for loop — Xatenev, Jun 06 '14 at 15:46
you are removing index 1 and its value,and in loop you are accessing it again. — ɹɐqʞɐ zoɹǝɟ, Jun 06 '14 at 15:47

AbraCadaver · Answer 1 · 2014-06-06T15:53:38.740

You need to reindex the array to loop over it with an incrementing number:

unset($a[1]);
$a = array_values($a);

for($i = 0; $i < count($a); $i++) {
    echo 'val at ', $i;
    echo " ", $a[$i], "\r\n";
}

Or just foreach the array:

foreach($a as $key => $val) {
    echo 'val at ', key;
    echo " ", $val, "\r\n";
}

For completeness, you can also merge with an empty array to reindex:

unset($a[1]);
$a = array_merge(array(), $a);

score 3 · Accepted Answer · answered Jun 06 '14 at 15:54

3

Are you wanting to remove a specific single array item, with re-indexing?

array_splice($a, $index_to_remove, 1);

answered Jun 06 '14 at 15:54

ludwigmace

692
4
10

user1978142 · Answer 3 · 2014-06-06T15:53:25.230

1

If you want to avoid undefined errors. You can use foreach

unset($a[1]);
foreach($a as $key => $value) {
    echo 'val as' . $key;
    echo ' ' . $value . "<br/>";
}

edited Jun 06 '14 at 15:53

answered Jun 06 '14 at 15:46

user1978142

7,946
3
17
20

score 1 · Answer 4 · answered Jun 06 '14 at 15:59

Reindex the array is the solution, remember you're removing one element and with the for iteration loops trough all items including index 1

<pre>
<?php

$a = array("foo", "baa", "ahahaha");

unset($a[1]);

$newarray = array_values($a); // here reindex the array
//echo '<pre>'; 
print_r($newarray);

for($i = 0; $i < count($newarray); $i++) {
    echo 'val at ', $i;
    echo " ", $newarray[$i], "\r\n";
}

?>

score 1 · Answer 5 · answered Jun 06 '14 at 16:08

I think your question has directed the unset error at the wrong place to be honest. Unset DID work. It was the "for" loop that created the error.

The problem you had was that, when you unset the key you removed the key name "1". It didn't then update the array index, and as a result, the array then contained only the keys "0" and "2". "1" did not exist.

Your "for" loop then tried to look at $a[1] and it wasn't there. Yes, there are two elements left but they aren't called "0" and "1" but "0" and "2".

Solution: To remove an element from an array, but then update the index you need to do this......

$r = 1; // The index number you want to remove.
array_splice($a,$r,1);

// Get value you removed?
$ir = array_slice($a,$r,1);
echo "Just removed $ir[0] from array";

Remove element from array, not using unset()

5 Answers5