Common Mistakes PHP Developers Make in 2024

PHP is a simple and approachable framework that has become more sophisticated over the years by introducing new features and functionalities with every update. The problem is that code-writing mistakes can lead to unforeseen consequences, and even the most skilled programmers are known to commit them.

Companies make it easy to hire PHP developers, but it is essential to watch out for common PHP mistakes. We will cover what they are in this post.

Top Mistakes That PHP Developers Need to Be Aware of

Below are some of the most common PHP mistakes that developers need to be aware of and avoid making:

1. Neglecting the Validation of Inputs

User inputs may be prone to errors, and never trust them is essential. PHP websites and apps are known to be subjected to cross-site scripting attacks, buffer overflows, and injection flaws. Missing or incomplete data is another common issue. Form validation is an essential aspect of PHP web development, and invalid data formats can lead to errors in results or outputs. There is also the chance of entering incorrect data ranges, and inputs may fall too high or low. User inputs must be properly sanitized to prevent malicious SQL code from being executed in the database. You can validate form data in PHP using built-in libraries and functions like preg_match() or filter_var() or a third-party library such as the Respect Validation Library.

2. Misunderstanding isset() Behavior

The isset() command in PHP returns items as false for ones that don't exist and null values. It is a behavior that confuses PHP developers. Take, for instance, this code snippet below:

$data = fetchRecordFromStorage($storage, $identifier);

If (!isset($data[‘keyShouldBeSet’]) {

                // change something here if ‘keyShouldBeSet’ is not set

}

The developer intended to see if keyShouldBeSet was set in $data.

!isset($data[‘keyShouldBeSet’]) will return false if the value is set to null.

A better option to check if a variable is set to null is to use array_key_exists().

3. Leaving Dangling Array References After Foreach Loops

Let’s use this code as an example:

$arr = array(1, 2, 3, 4);

foreach ($arr as &$value) {

       $value = $value * 2;

}

// $arr is now array(2, 4, 6, 8)

In the above code, the $value stays in scope and will retain a reference to the last element of the array. It can lead to unexpected consequences, and $value operations will inadvertently change the last element's value in the array once executed.

$value refers to a global variable and goes through each iteration, forming a pair of $arr references for the next element. After the end of the first traverse of $value, it will reference $arr the last element and remain in scope.

This behavior may cause some confusing bugs, and PHP developers may miss or be unable to detect them.

Let’s take this code below:

$array = [1, 2, 3];echo implode(',', $array), "\n"; foreach ($array as &$value) {}   //Traversing by referenceecho implode(',', $array), "\n"; foreach ($array as $value) {}     //Traversing by assignmentecho implode(',', $array), "\n";

The output for the snippet above will be:

1,2,3

1,2,3

1,2,2

You will notice that the last value of the last line is a two instead of 3.

There is an easy fix to this. Change the code to the lines below:

$arr = array(1, 2, 3, 4);

foreach ($arr as &$value) {

$value = $value * 2;

}

unset($value); // $value no longer references $arr[3]

The unset() variable will eliminate retained variable references and execute the next iteration correctly.

4. Ignoring UTF-8 & Unicode Issues

PHP developers must handle UTF-8 issues appropriately and avoid assuming all strings are treated as ASCII by default. Any code that doesn't handle non-ASCII strings may develop bugs. Developers can do PHP debugging and avoid this issue by learning the basics of UTF-8 and Unicode.

Replace old string functions with mb_* functions (the “Multibyte" extension must be included in the PHP build). Databases and tables should be using Unicode, and a good tip is that you can use JSON_encode () to convert non-ASCII symbols. However, serialize() won’t work.

Check and see if PHP code files are in UTF-8 encoding format. It will help avoid clashes during the concatenation of strings and work for hardcoded string constants.

5. Confusing Return by Reference with Return by Value

Let’s take this code snippet:

class Config

{

   private $values = [];

   public function getValues() {

       return $this->values;

   }

}

$config = new Config();

$config->getValues()['test'] = 'test';

echo $config->getValues()['test'];

The output for the code above will be:

PHP Notice: Undefined index: test in /path/to/my/script.php on line 21

So, what’s the issue?

The code will confuse returning arrays by reference with returning arrays by value. You need to explicitly tell PHP to return an array by reference since PHP will return an array by value by default. The called function and caller will be unable to access the same instance of the array and the getValues() call will return a copy of $values instead of its reference.

We can fix the issue by changing the above code to this:

class Config

{

   private $values = [];

   public function setValue($key, $value) {

       $this->values[$key] = $value;

   }

     public function getValue($key) {

       return $this->values[$key];

   }

}

$config = new Config();

$config->setValue('testKey', 'testValue');

echo $config->getValue('testKey');   // echos 'testValue'

The new code will allow the caller to set or acquire any value in the array without giving public access to the private $values array as well.

6. Performing Poor Backups or Failing to Do So

Some PHP developers may forget to create and run a backup while working on a project. It's crucial to perform proper backup so that you don't lose progress, and it can help save hours of recording. Run a backup throughout the PHP software development process and keep a separate client backup. In the rare case of critical failures, your clients will be able to navigate through challenging situations, and you can avoid operational downtimes.

7. Not Removing Development Configurations

PHP developers may hurry to finish a project and sometimes forget to remove the development configurations and variables before uploading them to production environments. Creating a development environment that duplicates the production environment for running live code is essential.

Moving directly from development to production without going through the staging process is a big mistake. Staging is critical for identifying issues that couldn't be caught early in development. It also helps make minimal changes and assists in cross-checking the code before it moves into production. To create a secure PHP application that can go live, remove configurations, and eliminate any bugs during the staging phase.

8. Not Following PHP Standards Recommendations

PHP coding standards are essential and can impact the PHP debugging process. Standardized code ensures consistency and is easy to work with. Your developer's productivity will peak, and you can spend less time on code maintenance.

The top five PHP coding standards are:

• PSR-0: Autoloading standard
• PSR-1: Basic coding standard
• PSR-2: Coding style guide
• PSR-3: Logger interface
• PSR-4: Autoloader

Following any one of the above PSR standards will do. It will make it easier for developers to grasp the code and quickly adhere to PHP standards recommendations.

9. Using the MySQL Extension

It is common knowledge that PHP no longer supports the MySQL extension. MySQL does not support SSL and is missing many modern features. PHP developers can work around this by using the MySQLI extension instead. Some of the significant benefits of MySQLI are – object-oriented interface support, multiple elements, and transactions. MySQL ensures that all queries are correctly written and won't cause performance issues for PHP applications.

10. Turning on Display Errors

PHP developers can be at risk of data breaches if they turn on error reporting. Many hackers look for error messages and exploit entry points from displayed information. Error reporting shows the site data and issues warning reports. These reports need to be kept hidden to maximize security. Turning off error reporting can speed up overall development time and take the guesswork out of PHP debugging.

11. Misusing Semicolons

This may seem like a silly mistake, but one that PHP developers take for granted. It is common to accidentally use a semicolon after a 'continue' or 'break' in the code. You can avoid it by using braces with PHP control structures.

Conclusion:

PHP developers are in high demand, but even the best developers may sometimes make these common mistakes. Awareness of these pitfalls is a part of the learning process, and it's completely okay. If you need help with a PHP development project or want to hire PHP developers, you can contact Clarion Technologies. We build offshore development teams and can handle everything from SEO optimization, UI/UX design, website management, QA, and software testing, and even provide DevOps consulting. Building your website using the PHP framework is a surefire way to ensure growth and success in today’s market, and you won’t regret it.