PHP Coding Standards and Best Practices with Examples

Introduction

PHP Programming is very popular and a lot of projects are still being developed today using PHP. The new version of PHP 8 is more powerful and so many developers, beginners and experienced, are working on PHP as of today. For any programming language we use, there must be standards and best practices to be followed by the developers. These standards and best practices help us to develop error-free software which is the most important quality feature of software. We must follow the coding standards and best practices for PHP as well.

Why do we need Standards and Best Practices?

Standards and best practices make us follow certain rules during project development. These rules are documented and developers including reviewers, team lead, project lead and overall organization should follow these rules. Without these, the software can result in defects, it can lead to confusion among the developers, and it may degrade in performance. In other words, spending unnecessary time and money could have been avoided if the standards were in place.

Some Best Practices for PHP development.

We are going to discuss here a few best practices and standards related to PHP development.

1. 1. Requirements and Design are reviewed and approved before development starts.

   This is not just for PHP development but this is valid for any project or any technology. Every project team has to go through the requirements and the feasibility study at the beginning of the project. Design is created based on the requirement. The project team must have a well-understood requirement and based on this the design has to be in place with proper review. Jumping into writing code without understanding what the customer wants will result in additional time and money because of rework. All the requirements may not be available at the beginning, but at least the part for which you are going to code should have a clear requirement.

2. 2. Creating a Development environment with the latest software versions

   A development environment has to be created with the required software. Review the list of software required. Use the latest and stable versions of PHP, MySQL (or any other database). It should be dedicated to the project only with proper access to the developers. Depending on the project size and complexity, a DBA and system or network administrator should be involved.

3. 3. Development Team with proper knowledge and experience.

   The project manager or lead decides the team. Experienced developers can help juniors follow coding standards and review their work. They can even document the standards for the project.

4. 4. Choose a better IDE (Integrated Development Environment) for coding.

   PHP does not need a specific editor or tool for writing the code. You can use a simple notepad to write a PHP program. However, there are many editors available which can be used for PHP development. Sublime editor is one example. Visual Studio Code (VS Code) gives a better environment for the developers. Writing code using VS code is faster, as many extensions are available that make developers' job easier. It provides integration with Git for version control as well.

5. 5. Use a Framework

   If you use an MVC framework, you automatically follow many best practices for PHP development. CodeIgniter, Laravel, and CakePHP provide environments for faster development. They provide a better structure for your application, provide securities and provide many useful libraries. So, whenever possible, use Framework for your development work.

6. 6. Use a Version Control tool

   Version control is a mandatory requirement for any project. We should maintain version control for all project-related documents and codes. This provides us with options to extract a previous or older version of the code when necessary. Also, it serves as a backup for your codes. Git is the most popular tool for this. So, enforce version control for the project.

7. 7. Optimize the Database

   If a database is used in the project, then all SQL statements should be analyzed by the DBA or an experienced developer for any potential performance issue. Make sure, you are using proper indexes. Incorrect joins between tables may lead to a cross-product that will degrade performance and result in fetching unwanted data.

8. 8. Coding Standards

   The project should have documented coding standards and should be followed by every developer. All developers should follow the same standards so that it is easier to debug code and maintain a clean, well-formatted and efficient code. The following standards are related to the programming code you write:

   • Add comments

     Give short but precise comments wherever necessary. A single line of comments with a date at the beginning is enough for the program. However, if you use a complex algorithm, you should add a summary of the logic in the comments so that a person supporting the application in the future understands it easily, instead of spending time going through the codes and understanding it. Even you yourself may not remember what logic you used in your own program; a single line of comment can save time in the future. Sometimes, if you use a meaningful name for a function, you may not need to add any comments on what the function does.

   • Naming Convention

     While naming a variable or a function, give a meaningful name to understand what purpose it is used for. There should be standards in naming variables and functions. For PHP variables and functions you can use all lower cases with an underscore between words (Snake Case) or with uppercase for the first letter of each word except the first one which is in lowercase (Camel Case).

     Examples of Snake Case - $avg_sal, $new_employee, function calculate_age(), function send_mail() etc.

     Examples of Camel Case - $avgSal, $newEmployee, function calculateAge(), function sendMail(). All developers should follow the same PHP naming conventions.

   • Format your code

     Format your code properly to understand it easily. Use proper indentation while using LOOP, IF…ELSE, SWITCH CASE, etc. This will give a well-formatted, clean and readable code. Of course, not just formatting, your program must work as per the requirement as well. So, develop a defect-free program and write in such a way, that it will be easier for another developer to maintain the code in the future.

   • Error Handling

     Error handling or exception handling is an important part of your program. You must handle errors and give proper error messages to the user. While working on database objects or working on files, raise proper exceptions, give proper messages and exit normally. There should not be any case where your program has an abnormal termination without a proper message. TRY...CATCH can be used to handle errors. Also make sure the error message does not display any sensitive information, like passwords.

   • Security

     Any form input data should be sanitized to avoid XSS (cross-site scripting) attacks. Convert special characters to HTML entities. An attacker can inject a piece of JavaScript code using <script> tag. Use the htmlspecialchars() function while taking input data from the form. You can use strip_tags() to remove HTML or PHP tags from a string. This will avoid such an attack.

     If you are using a database, avoid direct use of form input in the SQL statements. Use the Prepare() statement instead to avoid SQL injection.

     Avoid :

     Instead use below code using prepare():

Conclusion

A program that follows all applicable standards and meets the customer's needs is the best for the project. As a developer, you should strive to do that. It will reflect the developer's professionalism and the skills leading to a successful project. Happy coding ...