how to change the array key to start from 1 instead of 0 [duplicate]

Question

I have values in some array I want to re index the whole array such that the the first value key should be 1 instead of zero i.e.

By default in PHP the array key starts from 0. i.e. 0 => a, 1=> b, I want to reindex the whole array to start from key = 1 i.e 1=> a, 2=> b, ....

Answer 1

$alphabet = array("a", "b", "c");
array_unshift($alphabet, "phoney");
unset($alphabet[0]);

Edit: I decided to benchmark this solution vs. others posed in this topic. Here's the very simple code I used:

$start = microtime(1);
for ($a = 0; $a < 1000; ++$a) {
    $alphabet = array("a", "b", "c");
    array_unshift($alphabet, "phoney");
    unset($alphabet[0]);
}
echo (microtime(1) - $start) . "\n";


$start = microtime(1);
for ($a = 0; $a < 1000; ++$a) {
    $stack = array('a', 'b', 'c');
    $i= 1;
    $stack2 = array();
    foreach($stack as $value){
        $stack2[$i] = $value;
        $i++;
    }
    $stack = $stack2;
}
echo (microtime(1) - $start) . "\n";


$start = microtime(1);
for ($a = 0; $a < 1000; ++$a) {
    $array = array('a','b','c');

    $array = array_combine(
        array_map(function($a){
            return $a + 1;
        }, array_keys($array)),
        array_values($array)
    );
}
echo (microtime(1) - $start) . "\n";

And the output:

0.0018711090087891
0.0021598339080811
0.0075368881225586

Answer 2

Here is my suggestion:

<?php
$alphabet = array(1 => 'a', 'b', 'c', 'd');
echo '<pre>';
print_r($alphabet);
echo '</pre>';
?>

The above example will output:

Array
(
    [1] => a
    [2] => b
    [3] => c
    [4] => d
)

Answer 3

Simply try this

$array = array("a","b","c");
array_unshift($array,"");
unset($array[0]);

Answer 4

Ricardo Miguel's solution works best when you're defining your array and want the first key to be 1. But if your array is already defined or gets put together elsewhere (different function or a loop) you can alter it like this:

$array = array('a', 'b', 'c'); // defined elsewhere

$array = array_filter(array_merge(array(0), $array));

array_merge will put an array containing 1 empty element and the other array together, re-indexes it, array_filter will then remove the empty array elements ($array[0]), making it start at 1.

Answer 5

$array = array('a', 'b', 'c', 'd');
$array = array_combine(range(1, count($array)), array_values($array));
print_r($array);

the result:

Array
(
    [1] => a
    [2] => b
    [3] => c
    [4] => d
)

Answer 6

If you are using a range, try this code:

$data = array_slice(range(0,12), 1, null, true);

// Array ( [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 [6] => 6 [7] => 7 [8] => 8 [9] => 9 [10] => 10 [11] => 11 [12] => 12 )

Answer 7

I think it is simple as that:

$x = array("a","b","c");
$y =array_combine(range(1, count($x)), $x);
print_r($y);

Answer 8

I see this answer is very old, but my solution for this is by adding a +1 to your index. I'll do that because I think this is much faster and easy to read. When you print this it will start from 1 because 0+1 =1, then 2 etc.

  foreach($items as $index => $item){
 echo $index+1 . $item
}

Answer 9

$data = ['a', 'b', 'c', 'd'];
$data = array_merge([''], $data);
unset($data[0]);

I have found that this will perform slightly better, than the accepted solution, on versions of PHP 7.1+.

Benchmark code:

$start = microtime(1);
for ($a = 0; $a < 10000; ++$a) {
    $data = ['a', 'b', 'c', 'd'];
    $data = array_merge([''], $data);
    unset($data[0]);
}
echo (microtime(1) - $start) . "\n";

$start = microtime(1);
for ($a = 0; $a < 10000; ++$a) {
    $data = ['a', 'b', 'c', 'd'];
    array_unshift($data, '');
    unset($data[0]);
}
echo (microtime(1) - $start) . "\n";

Scripts execution time (PHP 7.4):

0.0011248588562012 
0.0017051696777344 

And the difference of these benchmarks will increase as the number of array values increases.

Answer 10

If you already have an array and want to reindex it to start from index X instead of 0, 1, 3...N then:

// Check if an array is filled by doing this check.
if (count($your_array) > 0) {
    // Let's say we want to start from index - 5.
    $your_array = [5 => $your_array[0], ...array_slice($your_array, 1)];
}

About spread operator "..."
https://www.php.net/manual/en/migration56.new-features.php#migration56.new-features.splat

P.S.

Real-world scenario/use-case, what I've met in work doing a task for a client:

I had one <div> that contains two <tables>. Each <table> contains markup for the days of the week. The first one has days from Monday to Thursday. The second one has days from Friday to Sunday. So, in my task, I had the variable represent a week in which each day had hours of open and close. I needed appropriately divide that week's variable into two.

<table>
    <?php for ($dayIndex = 0; $dayIndex < 4; $dayIndex++):  ?>
        <?php 
            $_timetable = array_slice($timetable, 0, 4);

            // $renderTimetableRow is an anonymous function
            // that contains a markup to be rendered, like
            // a html-component.
            $renderTimetableRow($_timetable, $dayIndex); 
        ?>
    <?php endfor; ?>
</table>

<table>
    <?php for($dayIndex = 4; $dayIndex < 7; $dayIndex++):  ?>
        <?php 
            if (count($_timetable = array_slice($timetable, 4, 7)) > 0) {
                $_timetable = [4 => $_timetable[0], ...array_slice($_timetable, 1)];
            }
        
            // $renderTimetableRow is an anonymous function
            // that contains a markup to be rendered, like
            // a html-component.
            $renderTimetableRow($_timetable, $dayIndex); 
        ?>
    <?php endfor; ?>
</table>

Answer 11

<?php
$home = ['hello','hii','bye','byee'];
$home = array_filter(array_merge(array(0), $home));
print_r($home);
// Ans
Array
(
    [1] => hello
    [2] => hii
    [3] => bye
    [4] => byee
);

?>

Answer 12

try this

<?php
$stack = array('a', 'b', 'c', 'd');
$i= 1;
foreach($stack as $value){
    $stack2[$i] = $value;
    $i++;
}
$stack = stack2;
?>