Core PHP Functions That Are Useful For WordPress Developers. Volume 2.

In the previous blog post, we reviewed some important fundamental PHP methods that are helpful for developers working on WordPress. Building on that foundation of knowledge, we are pleased to deliver Volume 2 of this guide, in which we will present additional basic PHP functions that will assist you in improving your WordPress programming abilities. If you are able to master these features, you will be able to develop WordPress sites that are stronger, efficient, and secure.


The array_merge() function is used to merge two or more arrays into a single array. This function is beneficial when combining arrays containing options, settings, or other data in your WordPress theme or plugin.

$array1 = array( 'apple', 'banana' );
$array2 = array( 'orange', 'grape' );
$merged_array = array_merge( $array1, $array2 ); // Result: array( 'apple', 'banana', 'orange', 'grape' );


The htmlspecialchars() function is essential for preventing cross-site scripting (XSS) attacks by converting special characters into their HTML entities. Using this function can help you ensure that your WordPress site remains secure when handling user-generated content. This has some similarities to the various WordPress escaping functions.

$input = '<script>alert("XSS attack!");</script>';
$safe_output = htmlspecialchars( $input ); // Result: '&lt;script&gt;alert("XSS attack!");&lt;/script&gt;'

trim(), rtrim() and ltrim()

These three functions are useful for removing whitespace or other characters from the beginning or end of a string or from the entire string itself. ltrim() trims characters from the beginning of a string, whereas rtrim() trims characters from the end of a string. trim() eliminates all of the characters from a string. With your WordPress theme or plugin, you may use these methods to clean up and check user input, as well as alter strings.

$string = '   Hello, world!   ';

$trimmed = trim( $string ); // Result 'Hello, world!'
$trimmed_left = ltrim( $string ); // Result: 'Hello, world!   '
$trimmed_right = rtrim( $string ); // Result: '   Hello, world!'


For counting the amount of elements in an array or the characteristics of an object, the count() method is the one to use. When you are dealing with loops, pagination, or handling data in your WordPress theme or plugin, you will find that this function is quite beneficial.

$array = array( 'apple', 'banana', 'orange', 'grape' );
$count = count( $array ); // Result: 4


To determine whether or not a variable contains no value, programmers make use of the empty() function. It gives a value of true if the variable does not have any value at all or if the value it does contain is one that is regarded as empty, such as null, false, or an empty string. For verifying user input or checking for the existence of data in your WordPress theme or plugin, this function is helpful.

$var1 = '';
$var2 = 'Hello, world!';

if ( empty( $var1 ) ) {
    echo 'Variable 1 is empty.';
} else {
    echo 'Variable 1 is not empty.';

if ( empty( $var2 ) ) {
    echo 'Variable 2 is empty.';
} else {
    echo 'Variable 2 is not empty.';


You will be able to become a more proficient and efficient WordPress developer if you master these essential PHP functions, in addition to the functions that were explained in the blog post that came before this one. If you take the time to learn the fundamental principles and functions of PHP, you’ll be in a much better position to develop WordPress plugins and themes that are both strong and safe. Maintain a curious attitude towards PHP’s large array of functions and strive to improve your programming skills on a consistent basis.