Content

• Introduction to C#
• Why use C# ?
• C# Syntax
• C# Output and Comments
• C# Variables
• C# Data Types

Introduction to C#

It is an object-oriented programming language created by Microsoft that runs on the .NET Framework.

C# has roots from the C family, and the language is close to other popular languages like C++ and Java.

C# is used to develop web apps, desktop apps, mobile apps, games and much more.

---

Why use C# ?

• It is one of the most popular programming language in the world
• It has a huge community support
• C# is an object oriented language which gives a clear structure to programs and allows code to be reused, lowering development costs.
• As C# is close to C, C++ and Java, it makes it easy for programmers to switch to C# or vice versa

---

C# Syntax

We can use below code to print "Hello World" on the console/screen

Example :

using System;

namespace HelloWorld
{
    class Program
    {
      static void Main(string[] args)
      {
        Console.WriteLine("Hello World!");    
      }
    }
}

• Line 1: using System means that we can use classes from the System namespace.
• Line 2: A blank line. C# ignores white space. However, multiple lines makes the code more readable.
• Line 3: namespace is used to organize your code, and it is a container for classes and other namespaces.
• Line 4: The curly braces {} marks the beginning and the end of a block of code.
• Line 5: class is a container for data and methods, which brings functionality to your program. Every line of code that runs in C# must be inside a class. In our example, we named the class Program.

---

C# Output and Comments

Output : We can get output of c# program on console/desktop application/web application etc.

Comments : Comments can be used to explain C# code, and to make it more readable. It can also be used to prevent execution when testing alternative code.

// This is a comment
Console.WriteLine("Hello World!");
            
/* The code below will print the words Hello World
to the screen*/
Console.WriteLine("Hello World!"); 

---

C# variables

Variables are containers for storing data values.

In C#, there are different types of variables like int,double,string,bool etc.

To create a variable, you must specify the type and assign it a value

However, you can add the const keyword if you don't want others (or yourself) to overwrite existing values (this will declare the variable as "constant", which means unchangeable and read-only):

string name = "Shree";
    
int myNum = 15;

const int myNumb = 95;

---

C# Data Types

A data type specifies the size and type of variable values. It is important to use the correct data type for the corresponding variable; to avoid errors, to save time and memory, but it will also make your code more maintainable and readable. The most common data types are:

Data Type	Size	Description
int	4 bytes	Stores whole numbers from -2,147,483,648 to 2,147,483,647
long	8 bytes	Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
float	4 bytes	Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits
double	8 bytes	Stores fractional numbers. Sufficient for storing 15 decimal digits
bool	1 bit	Stores true or false values
char	2 bytes	Stores a single character/letter, surrounded by single quotes
string	2 bytes per character	Stores a sequence of characters, surrounded by double quotes