Last updated on Feb 06, 2023
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Facebook is basically a social media platform. It is an American social media and social networking service, company that is to be accessed with the mobile network and this company is based in Menlo Park, California. Later it was introduced in the flagship process by the founder whose name is Mark Zuckerberg, he and his group of friends have designed this. Facebook is one of the largest social media sites these days and it is been used by millions of users from all over the world.

It is an attractive digital platform and people are connecting every day because the increasing rate of mobile devices is letting people use several social media accounts on different platforms. The candidates with knowledge in programming and IT sectors are always in demand on these social media platforms. Now let us discuss certain frequent, Facebook interview questions and answers often asked.

Here in this article, we will be listing frequently asked Facebook Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

Q1. How to convert infix to postfix and evaluate postfix expression?

One of the most important applications of the Stack is the arithmetic expressions’ conversion into the programming languages of high-level into a form that the machine can read. Because the computer system can understand as well as work only on the binary language, the system assumes that the arithmetic operation is able to take place only in two operands, for example, A+B, D/A, and others. But in the usual form, one arithmetic expression can consist of two or more operators plus two operands for example (A+B)*C(D/(J+D)).

Infix Expression

This expression follows this scheme that is an is being preceded as well as succeeded by the . This kind of expression is known as infix expression. For example, A+B, etc.

Postfix Expression

This expression follows this scheme that is an is being succeeded by two . For example, AB+, etc.

How to convert the Infix Expression To a Postfix Expression
Let, X, be one arithmetic expression that is written in the infix notation. Now, this algorithm finds or needs an equivalent postfix notation Y.
• Push “(“onto Stack, and add “)” to the end of X.
• Scan X starting from left moving to the right. Also, keep repeating Step 3 to Step 6 for every single element of X till the Stack gets empty.
• If the operand is met, add the operand to Y.
• If one left parenthesis is confronted, push the left parenthesis onto Stack.
• If the operator is met, then:
• Regularly jump from Stack then add to Y every single operator (that too on the top of the Stack) that has the exact same precedence or higher precedence than the operator.
• Add the operator to the Stack.
[here comes the end of If]
• Now, If one right parenthesis is confronted, then:
• Repeatedly jump from Stack then add to Y every single operator (that too on the top of the Stack) until one left parenthesis is met with.
• Then, remove the left Parenthesis.
[insert the parenthesis for End of If]
[here also insert the parenthesis for End of If]
• Finally, END.

Q2. Write a program to swap two numbers without using third variable in PHP?

You can two numbers without using the third variable in PHP as follows:

Example
```//swap two numbers without using third variable \$x=20; \$y=10; //add x and y, store in x i.e : 30 \$x=\$x+\$y; //subtract 10 from 30 i.e : 20 and store in y \$y=\$x-\$y; //subtract 20 from 30 i.e : 10 and store in x \$x=\$x-\$y; //now print the reversed values echo "Now x contains : ". \$x; echo "and y contains : ". \$y; //And you can make use of some predefined functions as well while not using the third variable. This can be done as follows: \$a = 10; \$b = 20; list(\$a, \$b) = array(\$b, \$a); echo \$a . " " . \$b;```
Q3. What is a social networking service?

There is a place or platform where you are able to connect or make new friends or connections. The people always find their matches or certain strangers those who have a similar career interest, hobbies, and background. This platform also allows you to do other tasks like you can add pictures, videos and other work you can perform here is also you can do blogging.

Q4. What is PHP?

PHP is basically known as the Hypertext pre-processor. It is a script based language where everything can be reused redesigned and adopted for any later use. The use of PHP is really efficient for web application designing. The web developers can use this programming language with a large extension to different operating systems and also due to access to different web servers. It is a real friendly programming language for developers. Here in this programming language script-based scripting is the main operation here where it enables the developer to help in the conversion of the program source and human-readable code into a much easier format which is really easy to understand by the system.

Q5. What is User Experience (UX)?

After an app is been launched in the market the user feedbacks or reviews must always be asked for. Because that will help you in designing or rectifying the flaws of your app and to make it more presentable as per the demand of the users. The user requirement must be always be asked for as finally, you are designing the app or the web page for them itself. Also certain developers before launching their app in the market. They even try to launch a test version of their app with similar ideas and if that works then it is fine to launch the final complete version of the app.

Q6. What Is AJAX? Explain.

AJAX is basically known as the Asynchronous JavaScript and XML, the unique function that it provides is that it helps to transfer the data from the server and also to the server without refreshing or reloading the entire page. While this entire process the user has no idea about the things going on the background as there is no interference or issues due to this process in the user experience.

Q7. What is the difference between the UI & UX?