Introduction

If you’re just starting out with PHP, you might feel overwhelmed by the hundreds of built in functions available. But don’t worry — you don’t need to learn them all at once.

In this blog, I’ll walk you through the top 5 PHP functions that I personally found most useful as a beginner — including real time examples I used while building forms, handling data, and debugging my first few web projects.

1. isset() Check if a Variable Exists

The isset() function in PHP is used to check if a variable is set and is not NULL. This is particularly useful when dealing with user inputs, session variables, API responses, or data retrieved from forms or external sources.

It helps prevent runtime errors and ensures that your code only tries to use variables that are available.

Key Points:

    • It returns true if the variable exists and is not null.

    • It returns false if the variable is not set or is null.

Real Example:

if (isset($_POST['submit'])) {
    echo "Form was submitted!";
}

Use Case:

You use this in contact forms or login systems to check whether a button or input field was filled before processing it.

2. explode() Split a String into an Array

The explode() function in PHP is a powerful and frequently used string function that splits a string into an array, using a specific delimiter (separator character). It’s like using a scissor to cut a long sentence into smaller words based on a pattern, such as a comma, space, hyphen, or any other character you define.

This function is extremely useful when working with data formats, CSV files, user input, or even URLs, where information is packed into a single string and needs to be separated for further processing.

Real Example:

$fruits = "apple,banana,orange";
$fruitArray = explode(",", $fruits);
print_r($fruitArray);

3. str_replace() Replace Text in a String

str_replace() searches for specific words or characters and replaces them. It’s useful for cleaning up input, formatting, or creating user friendly content.

function in PHP is used to replace all occurrences of a search string with a replacement string.

It works with:

    • Single strings

    • Arrays of strings

    • Case sensitive replacements

It’s fast, flexible, and does not modify the original string — it returns a new string with the replacement applied.

Real Example:

$text = "Hello {name}, welcome!";
$finalText = str_replace("{name}", "Akshita", $text);
echo $finalText;

Use Case:

I used this to dynamically show usernames in greeting messages on a dashboard page.

4. array_merge() Combine Multiple Arrays

The array_merge() function in PHP is a built in tool that allows you to combine two or more arrays into one unified array. It’s commonly used in scenarios where data is split across different arrays and needs to be merged for easier processing, analysis, or output.

This function is incredibly versatile and smart it can handle both indexed (numerically keyed) arrays and associative (string keyed) arrays, but it treats them differently depending on their type.

Real Example:

$a = ["red", "blue"];
$b = ["green", "yellow"];
$merged = array_merge($a, $b);
print_r($merged);

Use Case:

In one project, I had to merge default settings with user preferences array_merge() made it easy.

5. htmlspecialchars() Prevent XSS Attacks

The htmlspecialchars() function in PHP is a crucial built in tool that helps protect your web application from cross site scripting (XSS) attacks by converting special characters into their corresponding HTML entities. This makes any potentially malicious code safe to display on a web page.

It’s commonly used when displaying user generated content, such as comments, form inputs, or any data that comes from an external or untrusted source.

Real Example:

$name = "<script>alert('hack');</script>";
echo htmlspecialchars($name);

Use Case:

Essential when displaying user generated content like comments or form fields on your site.

Bonus Tip: How I Applied These in Real Projects

While building a basic blog and a user contact form, these functions helped me:

    • Validate user inputs

    • Sanitize form data

    • Split tag data for display

    • Merge arrays for dynamic settings

    • Replace placeholders in templates

Conclusion

Learning PHP doesn’t have to be overwhelming. These 5 functions — isset(), explode(), str_replace(), array_merge(), and htmlspecialchars()  are beginner friendly, powerful, and foundational to almost any project.

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New to PHP or working on your first dynamic website? Try these functions in your next project. If you need help with backend development or want to build a secure, fast PHP based website get in touch with our team today!