A set of general PHP interview questions along with sample answers. Remember that the actual questions may vary based on the specific role, project requirements, and the interviewer's preferences. Here are some common PHP interview questions along with possible answers:
1. Question: Explain the differences between GET and POST methods in PHP.
Answer:
- The GET method appends data to the URL, and the data is visible in the address bar. It is suitable for non-sensitive data.
- The POST method sends data in the HTTP request body, making it more secure for sensitive information like passwords or personal details.
2. Question: How does PHP manage sessions?
Answer:
- PHP manages sessions using a unique identifier (session ID) stored in a cookie or passed in the URL. Session data is stored on the server, and the session can be started using the
session_start()function.
3. Question: Explain the differences between 'include' and 'require' in PHP.
Answer:
- Both include and require are used to include files, but 'require' will generate a fatal error if the file is not found, whereas 'include' will only produce a warning.
4. Question: How can you prevent SQL injection in PHP?
Answer:
- To prevent SQL injection, use prepared statements and parameterized queries with either MySQLi or PDO. This helps to separate SQL code from user input, making it more secure.
5. Question: What is the purpose of the 'header' function in PHP?
Answer:
- The 'header' function in PHP is used to send raw HTTP headers to the browser. It is commonly used for tasks such as redirecting to another page, setting cookies, or controlling caching.
6. Question: How do you handle errors in PHP?
Answer:
- PHP provides various error-handling functions such as
error_reporting,ini_set, and try-catch blocks for exceptions. Logging errors is also essential for debugging and maintaining code.
7. Question: Explain the use of the 'explode' function in PHP.
Answer:
- The 'explode' function is used to split a string into an array based on a specified delimiter. For example:
php code
$string = "apple,orange,banana"; $fruits = explode(",", $string);
8. Question: How can you optimize the performance of a PHP application?
Answer:
- Performance optimization in PHP involves using caching mechanisms, optimizing database queries, minimizing file includes, and using proper coding practices. Additionally, utilizing opcode caching tools like OPcache can significantly improve performance.
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