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How to find the index of an element in an array using PHP?

By Shahnail Khan Last updated : February 19, 2024

In this article, we will look at the process of finding the index of an element within an array using PHP. Understanding array indexing is crucial, as it lays the foundation for efficient manipulation of data.

Finding the index of an element in an array using PHP

We will specifically deal with the array_search() function, a function that helps in locating elements within both indexed and associative arrays.

The array_search() function

The array_search() function is simple yet versatile. Its syntax is as follows:

array_search ('element', $array) 

Here, 'element' represents the target element, an element whose index needs to be found in a given array, and $array is the array in which the search is conducted. The function returns the index as an integer.

Now, let's take some examples to understand this function better.

Example 1: Searching for a Color in an Indexed Array

Suppose we have an indexed array consisting of different colors, and we want to find the index of the color "blue." Here's how you can use the array_search() function for this scenario:

<?php
// here we are creating an indexed array of colors.
$colors = ["red", "green", "blue", "yellow", "purple"];

// this line of code tells us the index of the color 'blue'
$index = array_search("blue", $colors);

// Display the result
if ($index !== false) {
    echo "The index of 'blue' is: $index";
} else {
    echo "'Blue' not found in the array.";
}
?>

Output

The output of the above example is:

The index of 'blue' is: 2

Example 2: Finding a Book Title in an Associative Array

Now, let's consider an associative array that consists of countries and their capitals. We have to get the index of a capital, namely "Tokyo" from the given array. Here's how you can use the array_search() function for this purpose:

<?php
// These lines of code create an associative array
// of countries and their capitals.

$countries = [
    "USA" => "Washington, D.C.",
    "Japan" => "Tokyo",
    "France" => "Paris",
    "Brazil" => "Brasília",
];

// this Line of code gets the index of 'Tokyo'.
$index = array_search("Tokyo", $countries);

// Displaying the result.
if ($index !== false) {
    echo "The index of 'Tokyo' is associated with the country: '$index'";
} else {
    echo "'Tokyo' not found in the array.";
}
?>

Output

The output of the above example is:

The index of 'Tokyo' is associated with the country: 'Japan'

In this example, we use the array_search () function to find the index associated with the capital city "Tokyo" in the associative array of countries and capitals.

Takeaway

Mastering array indexing in PHP is a fundamental skill for developers. The array_search() function provides a convenient way to locate elements within arrays, whether they are indexed or associative. By adopting this approach, you can enhance the efficiency of your code while ensuring the flexibility needed for various data structures.

To understand the above examples, you should have the knowledge of the following PHP Topics:

• PHP Basic Syntax
• PHP Comments
• PHP Conditional Statements
• PHP Arrays

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