PHP Indexed Arrays

In PHP, an indexed array is a type of array where each element is assigned an index number. By default, the index of the first element starts at 0, the second element gets index 1, and so on. This sequential indexing makes it easy to access and manipulate array elements.

• Sequential Indexing: The first element is indexed at 0, the second at 1, and so on.
• Dynamic Size: Indexed arrays can grow and shrink without needing to declare their size in advance.
• Flexible Data Types: You can store various data types like integers, strings, booleans, and floats in an indexed array.

Creating an Indexed Array

Indexed arrays in PHP can be created in two ways:

1. Using the array() function

<?php
$colors = ["red", "green", "blue", "yellow"];
?>

2. Using the short syntax (square brackets)

<?php
$fruits = ["apple", "mango", "litchi"];
?>

3. Accessing Elements in an Indexed Array

You can access elements in an indexed array by referring to their index number.

<?php
 $pen = ["Parker", "Flair", "Cello"];
echo $pen[0];  
?>

Parker

4. Modifying Array Elements

To modify an array element, simply refer to its index and assign a new value.

<?php
$numbers = [10, 20, 30, 40];
$numbers[2] = 35;
var_dump($numbers);  
?>

array(4) {
  [0]=>
  int(10)
  [1]=>
  int(20)
  [2]=>
  int(35)
  [3]=>
  int(40)
}

5. Looping Through Indexed Arrays

PHP provides multiple ways to loop through indexed arrays. The most common way is using a foreach loop.

<?php
  $cars = ["Volvo", "BMW", "Toyota"];
foreach ($cars as $car) {
    echo "$car"."\n";  // Output: Volvo, BMW, Toyota
}
?>

Volvo
BMW
Toyota

Another way is by using a for loop, especially when you need to access both the index and value.

<?php
$countries = ["USA", "Canada", "Mexico", "Brazil"];
for ($i = 0; $i < count($countries); $i++) {
    echo $countries[$i] . "\n";
}
?>

USA
Canada
Mexico
Brazil

6. Adding New Items

You can use the array_push() function to add new items to an indexed array. PHP will automatically assign the next available index.

<?php
  $colors = ["red", "green", "blue"];
array_push($colors, "black");
var_dump($colors);  

?>

array(4) {
  [0]=>
  string(3) "red"
  [1]=>
  string(5) "green"
  [2]=>
  string(4) "blue"
  [3]=>
  string(5) "black"
}

7. Removing Items from Indexed Arrays

You can remove items from an indexed array using the array_pop() function, which removes the last item from the array.

<?php
$vegetables = ["carrot", "tomato", "cucumber", "lettuce"];
array_pop($vegetables);
var_dump($vegetables);  
?>

array(3) {
  [0]=>
  string(6) "carrot"
  [1]=>
  string(6) "tomato"
  [2]=>
  string(8) "cucumber"
}

8. Traversing an Indexed Array

An indexed array can also be traversed in reverse order using a while loop.

<?php
$numbers = [1, 2, 3, 4, 5];
$i = count($numbers) - 1;
while ($i >= 0) {
    echo $numbers[$i] . "\n";
    $i--;
}
?>

5
4
3
2
1

Built-in Functions for Indexed Arrays

PHP provides several built-in functions to work with indexed arrays. Some of the most common functions include:

• array_push($array, $value): Adds one or more elements to the end of the array.
• array_pop($array): Removes the last element from the array.
• array_shift($array): Removes the first element from the array.
• array_unshift($array, $value): Adds one or more elements to the beginning of the array.

Conclusion

Indexed arrays are one of the most commonly used data structures in PHP, allowing you to store and manipulate collections of data efficiently. They provide simple and flexible ways to store, access, and modify elements using numeric indexes. With built-in functions and loops like foreach, for, and while, you can easily traverse and manipulate indexed arrays.