Creating Arrays

PHP provides two primary methods for constructing arrays:

1. Using the built-in function: array()
2. Utilizing shorthand notation with square brackets.

For example, the following demonstrates these methods:

$my_array = array(1, 2, 5, 9);

$another_array = [0, 1, 2];

To determine the number of elements within an array, the count() function can be used:

echo count($my_array); // Outputs 4

Accessing Elements

To retrieve a specific element from an array, index notation is applied. Since array indexing starts at 0, to access the second element in an array named $my_array, you would use the following syntax:

$my_array = [1, 2, 3, 4];

echo $my_array[1]; // Outputs 2

Modifying Arrays

Once an array has been established, it can be modified in several ways. For example, to append an element to the end, you can use square brackets:

$my_array = [0, 1, 2];

$my_array[] = 3; // The array now becomes [0, 1, 2, 3]

To alter an existing item in the array, specify the index of the item you wish to change and assign a new value:

$my_array = [1, 2, 3, 4];

$my_array[2] = "new value"; // Now $my_array is [1, 2, "new value", 4]

Array Methods

Array methods are functions that enable us to modify or manipulate arrays more efficiently. Here are some commonly used methods:

• array_push(): This method adds one or more elements to the end of an array.

$my_array = [1, 2, 3];

array_push($my_array, 4, 5);

// Now $my_array is [1, 2, 3, 4, 5]

• array_pop(): This method removes the last element from an array.

$my_array = [1, 2, 3, 4];

array_pop($my_array);

// Now $my_array is [1, 2, 3]

• array_unshift(): This method adds one or more elements to the beginning of an array.

$my_array = [1, 2, 3];

array_unshift($my_array, 0);

// Now $my_array is [0, 1, 2, 3]

• array_shift(): This method removes the first element from an array.

$my_array = [1, 2, 3];

array_shift($my_array);

// Now $my_array is [2, 3]

Nested Arrays

As previously mentioned, arrays can store mixed data types, including other arrays. A nested array example would be:

$my_array = [[1, 2], [3, 4], [5, 6]];

To access elements in a nested array, you can use index notation for both the outer and inner arrays:

echo $my_array[1][0]; // Outputs 3

Associative Arrays

An associative array, or map, is a data structure where elements are accessed by keys rather than indices. This is akin to a dictionary where each key is linked to a corresponding value. For instance, if you wanted to maintain a list of friends' ages, an associative array would be much more intuitive:

$friends_ages = ["Bob" => 23, "Clive" => 49, "Amelia" => 15];

To access an element, use the key instead of an index:

echo $friends_ages["Bob"]; // Outputs 23

Adding a new element to an associative array involves specifying the new key and its associated value:

$friends_ages["Sara"] = 26;

// Adds a key for Sara with her age

To remove an element from an associative array, the unset() function is utilized:

unset($friends_ages["Clive"]);

// Removes Clive from the array

Finally, to update an existing value in an associative array, simply refer to the key and assign a new value:

$friends_ages["Bob"] = 24;

// Updates Bob's age to 24

For those of you embarking on your PHP learning journey, I hope this introduction proves helpful, and I invite you to follow along with the other articles in this series.

Links to Additional PHP Resources

• Should You Still Learn PHP in 2022?
• PHP 101: Fundamentals
• PHP 101: Functions
• PHP 101: Arrays
• PHP 101: Conditionals
• PHP 101: Loops (coming soon)
• PHP 101: Form Handling (coming soon)
• PHP 101: Classes and Objects (coming soon)
• PHP 101: My First Project (coming soon)

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