FAQ

FAQ _unofficial

Please comment other frequently asked questions and their answers and I'll add them.

Make sure to follow the Content Creation Guidelines when posting on Q&A. And read about How to maximize your chances of receiving useful answers in forums.

More FAQ and the thread that inspired this can be found here. And the official FAQ.

General
Java
Web
C++
C#
Python
Ruby
Swift

Which language should I learn first?

That strongly depends on what you want to do.
For web development start with HTML, CSS and JavaScript.
For beginning with programming in general, choose Python or Ruby.
If you want to program Android apps, Java is your best choice.

What is XYZ?

Please use Google to get the information you need.

What's the difference between x++ and ++x / x-- and --x?

++x increments the value of x (x = x + 1) and then uses it.
x++ uses the value of x before increasing it.
-- decreases the value (x = x - 1).

Examples:
x=5; // x is 5 cout<<x++; // outputs 5, but x is now 6

x=5; // x is 5 cout<<++x; // x is now 6, outputs 6

Can I use the certificates for job applications?

No.
These certificates aren't official. Since you can use hints and have unlimited tries to answer the questions, everyone eventually gets the certficates.

Why is there no course for XYZ?

There are a lot of programming languages out there. If you think one particular language is missing, use the feedback form to suggest it. You'll find it in the app in the menu (top right corner).

Why is there no challenge for XYZ?

SQL: Maybe because the questions would be way to long as you'd need to have the contents and structure of a database to relate the questions to.

CSS: You'll find questions about CSS in the HTML challenges. CSS won't work without HTML so it makes perfectly sense.

Others: Maybe SoloLearn will add them in the future. Just be patient.

How do I learn to hack?

Just. Don't.
If you really want to learn how to hack, learn C-languages and become familiar with the system. You'd have to learn the rest by yourself or somewhere else. But please don't become a so called skript kiddy!

How do I verify my account?

Check all folders of the email account that is related to your profile. SoloLearn has sent you an email to verify your account. Open the link in the email.
Tashi N

What are challenges in SoloLearn? How do they work?

Challenges are initiated by challenging another user in the Challenge section using a certain weapon (language). Challenges consist of 5 relevant programming questions which has to be completed by both users within a limited amount of time. The user with the most correct answers wins. If both sides get equal amount of correct answers, the challenge ends in a draw.

After initiating and completing 5 questions of the challenge session, the user who initiated the challenge will have to wait until the other user comes online and accept the challenge. Users have the option to decline the challenge. If the other user does not respond to the challenge invitation, the challenge will simply expire.

Users gain XP for winning challenges, and lose XP for losing challenges. The base algorithm of the XP system in challenges is as such:
Lose XP = 32 - Win XP

Answer bonus may also be given to beginners.
Hatsy Rei

Can you write a program that does ... for me?

No! Do your homework on your own. If you're stuck, provide the code you already have and specify what's your problem.

How do I become a mod?

Read this: https://www.sololearn.com/discuss/306928/?ref=app
Tashi N

How do I get more followers?

Be helpful in the community, post top codes, do tons of challenges.
Pixie

Read this: https://www.sololearn.com/discuss/300519/?ref=app Tashi N

What is the modulus operator (%)?

The modulus operator calculates the remainder of an integer division.
For example: 5 % 3 = 2 because 3 fits once into 5 and 5 - (3 * 1) = 2
Another example: 21 % 4 = 1; 21 - (4 * 5) = 1
And another: 15 % 5 = 0; 15 - (5 * 3) = 0

What's your favorite ...?

There's a great code for polls made by Burey. Check it out. That's way better than trying to find out what's popular via Q&A ;)

How do I submit feature requests?

There are two ways:

Use the feedback function in the app (top right corner menu > Feedback)
Write an email to info@sololearn.com

Can I create games in language XYZ?

Of course. Back in the days when operating systems didn't have fancy GUIs, there where a lot of text based games. These can be played in the console. If you prefer graphic based games, there are tutorials on how to make clones of Tetris, Pong or Snake with HTML5/JS, Java, C++ and others. Or try to make a quiz game like "Who wants to be a millionaire?" with HTML5, JavaScript, PHP and mySQL.

You can find some examples in the code playground.

Do you want to join my WhatsApp group?

Most people here prefer to get in contact with you at the Q&A section. If you really want them to join - write a good code to show your skills and invite them to yoin your group there.
Tashi N

Why should I comment my code?

Use comments as a documentation for your code. They'll help you (and others) to understand what parts of the code does. This comes in handy when you re-read your code after several months or if others want to understand your code.

You can use comments also for debugging. Just comment out the faulty lines and try to run your program again. You can then remove the comment step by step until you find the error. Or maybe you need to enter a username and password to run your program, just comment out the login, so you can use your program without any credentials.

You'll find an overview of how to comment in different languages in the Wikipedia.

Where do I get Java and other neccessary software? (JRE/JDK, IDEs, Android Studio)

You can download Java from Oracle. Get the latest JDK (Java SE Development Kit.

If you need an IDE for programming in Java, there are Eclipse, Netbeans or IntelliJ IDEA. There are others too, but those three seem to be the most popular ones.

Android Studio is available at Google Developers.
Burey

What's the difference between Java and JavaScript?

Java is a programming language running in the Java Virtual Machine (JVM), whereas JavaScript is a scripting language interpreted by a web browser. They only have the name in common as Java was very popular when JavaScript was created and the developers of JavaScript thought it would make their language equally popular when they put Java into its name.

Which text editors should I use for web development?

The most popular one seems to be Notepad++. But there's also Atom, Adobe Brackets and Sublime Text, which run on Windows, Linux or Mac. They're all free.

How do I publish my website online?

Search for a hoster which fits your needs (free, enough space, support for php/mysql and so on). There are plenty. Nearly all of them provide manuals on how to upload to their service.

What's the difference between id and class?

An id is unique. It refers to one element. It may occure only once in the document.

Classes define several related elements. If a class is addressed (e.g. by CSS or JavaScript) all elements belonging to that class are affected.

What is Bootstrap?

Bootstrap is an open-source JavaScript framework developed by the team at Twitter. It is a combination of HTML, CSS and JavaScript code designed to help build user interface components. Bootstrap was also programmed to support both HTML5 and CSS3.

Also it is called front-end-framework.

Bootstrap is a free collection of tools for creating websites and web applications.

It contains HTML and CSS based design templates for typography, forms, buttons, navigations and other interface components, as well as optional JavaScript extensions.

Button demo:

Burey

Lots of detailed examples can be found on W3Schools, you'll find Snippets on Bootsnipp and free themes on Bootswatch.

What is the <span> tag?

Taken from W3Schools:
It's used to group inline-elements in a document. It provides no visual change by itself. It provides a way to add a hook to a part of a text or a part of a document.

You can use it to style parts of your document individually without using other, semantically not fitting tags. <span> is also often used for interaction with JavaScript or to insert images from an image sprite via CSS.

Where do I find compilers/IDEs for C++?

You can use Microsoft Visual Studio or Code::Blocks. If you like Eclipse for Java, use it's C++ compiler.

What's the difference between C and C++ and C#?

C++ is "C and a bit more". C++ added more functionality to C. C# was created by Microsoft to add even more to C and C++ and to be used with the .NET-Framework.

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What does i in the loop mean?

It's a variable used as iterator/index. It doesn't have to be i, it could be a, iterator, index, somethingelse, oewbgwogncvewg or any other valid variable name.

Sample code:
for i in range(1,10): print i

What is the difference between / and //?

They're both used for division, / results in a float division, whereas // results in an integer division.

Example (only Python3; in Python2 both would result in integers unless at least one operand is a float):

10 / 3 = 3.3333333333333335

10 // 3 = 3

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