How to Insert Elements into PHP Arrays at Specific Positions?

Inserting Elements into Arrays at Specific Positions

Inserting elements into arrays at specific positions is a common task that can be accomplished through a combination of slicing and union operators.

Suppose we have two arrays:

$array_1 = [
  '0' => 'zero',
  '1' => 'one',
  '2' => 'two',
  '3' => 'three',
];

$array_2 = [
  'zero' => '0',
  'one' => '1',
  'two' => '2',
  'three' => '3',
];

Our goal is to insert the array ['sample_key' => 'sample_value'] after the third element of both arrays.

Solution:

The array_slice() function allows us to extract portions of an array. We can combine this with the union array operator ( ) to recombine the parts in the desired order. The following code achieves our goal:

$res = array_slice($array, 0, 3, true) +
    ["sample_key" => "sample_value"] +
    array_slice($array, 3, count($array) - 1, true);

In this example:

• array_slice($array, 0, 3, true) extracts the first three elements of $array. The true argument ensures that the keys are preserved.
• ["sample_key" => "sample_value"] is the element we want to insert.
• array_slice($array, 3, count($array) - 1, true) extracts the remaining elements of $array starting from the fourth element.

Upon combining these parts using the union operator, the resulting array has the desired order:

print_r($res);

Output:

Array
(
    [zero] => 0
    [one] => 1
    [two] => 2
    [sample_key] => sample_value
    [three] => 3
)

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