PHP's array_push() function is used to add one or more elements to the end of an array. This function modifies the original array by appending the new elements and returns the new number of elements in the array. Below is an in-depth explanation of the function, its syntax, examples, and some related considerations.

Syntax

int array_push(array &$array, mixed ...$values)

• Parameters:

  • &$array: The input array passed by reference. This means that any changes made by the function will directly affect the original array.
  • ...$values: One or more values to be pushed onto the end of the array. You can pass multiple values separated by commas.

• Return Value:

  • The function returns an integer that represents the new number of elements in the array after the values have been pushed.

Detailed Explanation

1. Passing the Array by Reference

The array is passed by reference (indicated by the & symbol). This allows the function to modify the original array rather than working on a copy of it.

2. Adding Multiple Elements

You can push multiple elements onto the array at once. The elements are added in the order they are provided.

3. Return Value

After execution, array_push() returns the count of the array’s elements. This can be useful if you need to know the updated size of the array immediately after the push operation.

Examples

Basic Example

Below is a simple example showing how to push elements into an array.

<?php
// Define an initial array
$fruits = array("apple", "banana");

// Use array_push to add more elements
array_push($fruits, "orange");

echo "Number of elements after push: " . count($fruits) . "\n";  
print_r($fruits);
?>

Output:

Number of elements after push: 3
Array
(
    [0] => apple
    [1] => banana
    [2] => orange
)

Example with Multiple Values

You can push multiple elements in a single function call:

<?php
// Define an initial array of colors
$colors = array("red", "green");

// Add multiple elements to the array
$new_count = array_push($colors, "blue", "yellow", "purple");

echo "New element count: " . $new_count . "\n";
print_r($colors);
?>

Output:

New element count: 5
Array
(
    [0] => red
    [1] => green
    [2] => blue
    [3] => yellow
    [4] => purple
)

Using array_push with an Empty Array

The function works seamlessly with an empty array, adding elements to it from scratch:

<?php
// Create an empty array
$numbers = array();

// Push values into the empty array
$new_count = array_push($numbers, 1, 2, 3, 4);

echo "Total elements: " . $new_count . "\n";
print_r($numbers);
?>

Output:

Total elements: 4
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
)

Alternative Methods

While array_push() is a concise and clear method to append elements, it’s also common to use the shorthand notation $array[] = $value; for adding single elements. For example:

<?php
$numbers = array();
$numbers[] = 1;
$numbers[] = 2;
$numbers[] = 3;

print_r($numbers);
?>

This will yield the same result as pushing the elements one by one with array_push(). Note that the shorthand is suitable when adding one element at a time.

Points to Consider

• Performance: When adding a single element to an array, the shorthand $array[] = $value; might be marginally faster than using array_push() because it does not involve a function call overhead. However, when adding multiple elements at once, array_push() can be more concise.

• Array Type: The function works with any indexed array. If you try to use array_push() on an associative array, the new elements are added with numeric keys, which might not be the intended behavior for all use cases.

• Error Handling: If the first parameter is not an array, PHP will emit a warning and the behavior will be unpredictable. Always ensure that your variable is an array before using array_push().