1. What is PHP?
PHP is a general-purpose scripting language that is especially suited to web development. It is a server-side language, meaning that the code is executed on the web server and the results are sent to the user’s browser. PHP is free and open source, and it is one of the most popular programming languages in the world.
2. What are some of the common uses of PHP?
PHP is commonly used to develop dynamic websites and web applications. It can also be used to develop command-line tools, desktop applications, and mobile applications.
3. What are the different types of variables in PHP?
There are four types of variables in PHP:
- Scalar variables: Scalar variables can store a single value, such as a string, number, or boolean.
- Compound variables: Compound variables can store multiple values, such as an array or object.
- Resource variables: Resource variables represent external resources, such as a file or database connection.
- Null variables: Null variables represent a lack of value.
4. What are the different types of loops in PHP?
There are three types of loops in PHP:
- For loops: For loops are used to iterate over a specific number of times.
- While loops: While loops are used to iterate over a block of code until a condition is met.
- Do…while loops: Do…while loops are similar to while loops, but the block of code is executed at least once, even if the condition is not met.
5. What is the difference between a function and a method?
A function is a block of code that can be reused throughout a program. A method is a function that belongs to a class or object.
6. What is the difference between a class and an object?
A class is a blueprint for creating objects. An object is an instance of a class.
7. What is the difference between an associative array and an indexed array?
An associative array is an array where the keys are strings. An indexed array is an array where the keys are integers.
8. What is the difference between a POST request and a GET request?
A POST request is used to send data to the server. A GET request is used to retrieve data from the server.
9. What is the difference between a cookie and a session?
A cookie is a small piece of data that is stored on the user’s browser. A session is a way to track a user’s activity across multiple pages of a website.
10. What is the difference between include() and require()?
The include() function includes a file, but it continues executing the script even if the file is not found. The require() function includes a file, and it halts execution of the script if the file is not found.
11. What is the difference between echo and print()?
The echo function outputs a string to the browser. The print() function outputs a string to the browser and returns a value.
12. What is the difference between header() and location()?
The header() function sends a header to the browser. The location() function redirects the user to a new page.
13. What is the difference between mysql_ and mysqli_?
The mysql_ functions are the older MySQL functions. The mysqli_ functions are the newer MySQL functions.
14. What is the difference between PDO and mysqli_?
PDO is a database abstraction layer that allows you to connect to different types of databases using the same code. mysqli_ is a specific driver for connecting to MySQL databases.
15. What is the difference between isset() and empty()?
The isset() function checks if a variable is set. The empty() function checks if a variable is empty.
16. What is the difference between === and ==?
The === operator checks if two values are equal and of the same type. The == operator checks if two values are equal, but it does not check the type.
17. What is the difference between exit() and die()?
The exit() function terminates the script and returns a status code. The die() function terminates the script and returns a message.
18. What is the difference between error_reporting() and error_get_last()?
The error_reporting() function sets the error reporting level. The error_get_last() function returns the last error that