C# Q&A : Part 1

Welcome to this new series of C# Q&A.
This's a 2 part series and this's part 1 , from now onwards , I'll be covering many questions which are going to be distributed on a 2 posts long series , the series will cover 20 questions , some will be accompanied with coding examples , however , everything is going to be beginner friendly and I'll try my best to further simplify any perplexing concepts if we stumbled upon any.

So , without further ado , let's kick off part 1

1: What's a class ?

A class is a defining structure or a template to create an object , it contains properties , data fields , indexers and methods.

We can create many instances of a class.

2: What's a namespace ,And is it compulsory ?

A namespace is basically a way of wrapping/organizing classes of the same group or relative functionality under the same name , which is up to you to specify , by importing a namespace to your code file , you can access all the grouped functionality that resides within that namespace , I like to think of a namespace as a tool box , when you bring that box and open it , you can start employing the tools inside it and put them to work.

One namespace we all use is the System namespace , by doing the following :

using System;

By adding this line to our code , we can start using things like the Console Static Class and the like.

Are namespaces compulsory ? No
But it's a best practice so you end up with more maintainable code as an outcome.

3: What're Value Types & Reference Types ?

Value Type: Contains the value directly , an example could be this:

int i = 10;

Reference Type: Contains a reference to a memory address in which the value is stored , an example would be a string like the following:

string message = "Hello , DevCommunity !";

The message variable doesn't directly contain the value given to it , rather it contains a reference for the memory address where the message is stored.

4: What're the comment variations in C# ?

1: Single-line comments //A single line comment
2: Mutli-line comments /*A multi line comment */\
3: XML comments ///<summary>

5: Is C# code managed ?

Yes , C# code is managed cause the Common Language Runtime or CLR for short , compiles the code to Microsoft Intermediate Language or MSIL.

Managed Code: Managed code is essentially code whose execution is managed by a runtime.

6: What's an interface ?

An interface , like a class , can contain properties , indexers , and methods , although , unlike a class , interfaces only include the declaration of the members and not the concrete implementation , an interface might also be referred to as a contract , it merely contains declarations , and the implementation of the members is then left to the classes which implement that interface.

7: How to implement an interface ?

Well , implementing an interface is identical to inheriting a class , an imaginary example snippet could be used for demonstration purposes goes like this:

public interace IService
{
    public void SayHi();
}

public class Greeter : IService
{
    public void SayHi()
    {
        Console.WriteLine("Hi There !");
    }
}

Quick Note: It's a convention when naming interfaces to precede the interface name with an I , it doesn't have anything to do with errors or anything else , but it's just a convention to follow , so always name your interfaces like that.

8: What's the virtual keyword used for ?

When a member is marked as virtual , it must be implemented in the class where it's defined , BUT , it can then be overridden by the classes inheriting that class in which the virtual member lives.

9: What's method overloading ?

It's possible to have methods that share the same name in the same class , although , they shouldn't match in their signatures , but what's a method signature ?
A method signature is the method's name and set of parameters it accepts.
An example of method overloading is the WriteLine method that belongs to the Console static class , this method has 18 overloads , they all differ in the parameter set.

Let's see how we can achieve method overloading:

public void SayHi()
{
    Console.WriteLine("Hi");
}

public void SayHi(string name)
{
    Console.WriteLine($"Hi {name}");
}

Same name + Different parameters set = Different Signature.
Like that

Final Question

10: What's a static class ?

A static class solely contains static methods , properties , or in short , static members only , additionally , static classes are sealed , which implies they cannot be inherited , or used to create instances , an example of a static class that I mentioned multiple times previously , is the Console class , when you call Console.WriteLine(); , you don't actually create a new instance of the console , you're using the same console again and again , because no need arises to have instances of the console , and that's why static classes can be beneficial.