PHP technical interview FAQs and answers

PHP technical interview FAQs and answers

As one of the most popular server-side programming languages ​​today, PHP has a wide range of uses and strong community support. For beginners or people who want to engage in PHP development, they often encounter many difficulties during interviews. This article summarizes some common PHP interview questions and their answers, hoping to be helpful to readers.

1. What is PHP?

PHP (Hypertext Preprocessor) is an open source scripting language used for server-side programming. It supports various databases, including MySQL, PostgreSQL, Oracle, etc., and can generate documents in HTML, XML and other formats.

2. What is the difference between PHP and JavaScript?

PHP and JavaScript are both scripting languages, but their main uses are different. PHP is generally used for server-side programming, while JavaScript is mainly used for client-side programming. PHP can handle various databases, while JavaScript does not support database operations. In addition, PHP uses the PHP interpreter, while JavaScript uses the JavaScript engine in the browser.

3. Explain PHP’s automatic type conversion.

PHP's automatic type conversion means that when running PHP code, if the program finds that the type of a variable is inconsistent with the required type, it will automatically convert it to the required type. For example, the result of "1" 2 is 3 because PHP automatically converts the string "1" to a numeric type. However, when writing PHP programs, be aware that automatic type conversion may cause unexpected results in the program and should be used with caution.

4. What is the difference between include() and require() in PHP?

include() and require() are both used to introduce files, but their difference lies in the way the file is not found. If you use include() to introduce a file, if the file is not found, the program will prompt a warning, but the program will continue to execute. And if you use require() to introduce a file, if the file is not found, the program will directly stop execution.

5. Explain the application of object-oriented programming (OOP) in PHP.

Object-oriented programming is a programming idea, the core of which is to divide a program into objects that can interact and communicate. In PHP, object-oriented programming is implemented using classes, which can contain properties and methods. Instances of classes are objects, and you can use objects to access properties and methods. This programming method can improve code reusability and maintainability.

6. How to avoid SQL injection?

SQL injection is a common attack method. Attackers can perform illegal database operations by inserting malicious code into query statements. To avoid SQL injection, you can use prepared statements or parameterized queries. Prepared statements refer to replacing placeholders with variables before executing the query statement, and then executing the query statement. This can prevent malicious code from being inserted. Parameterized query statements refer to using parameters in the query statement instead of splicing variables directly into the query statement. This can also effectively prevent SQL injection attacks.

7. How to debug PHP program?

To debug PHP programs, you can use a debugger, such as Xdebug. Use a debugger to step through a program, view variable values ​​and program flow, and find problems in the program. In addition, using PHP's error log is also a way of debugging. When an error occurs, the program will record the error information in the log. You can find the location and cause of the problem by viewing the log.

Summary

The above are common questions and answers in PHP interviews. These questions cover many aspects such as basic knowledge of PHP, object-oriented programming, database operations, etc. Readers can learn and practice based on their own actual situations to better cope with PHP interviews.

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