text: A function is a block of code that contains statements to be executed when needed. In other words, functions are known as methods. In C#, the method is a collection of properties to create functionality.
  A programmer makes code to execute the application. Programmer can divides codes into functions to make code easier. Every function performs a different task.
  In C# programming, we create a function using the function name.
  function_name - It is the name of the function. A programmer can create a function with any unique name. The function name is used to call function. Programmer can create a functional name according to function behavior. In C# or another language, behavior denotes the functionality of function.
  Return Type - A function can return a value. The return type indicates the data type of function return.
  Block - Function functionalities are created inside the block. The block start and end with curly braces. Inside the block, we define the behavior of that function. A block is known as the body of function that contains statements to be executed.
  Parameters - A parameter is like a placeholder. Parameter is a list of argument(S). It can be passed in a function during call time. When a function invoked, you pass a value to the parameter. We can create function with argument(S) or without arguments.
  Access Specifier - Access specific set the accessibility of function functionality outside or inside. There is three access specifier in C# programming.
  1. Public
  2. Private
  3. Protected.
  The biggest thing is to know how to declare the function in C# programming.
  Let's understand with a syntax.
  Function_Name( ) { //body , block of code //return statement }
  In the above syntax, the access specifier, parameter, and return are not mandatory. These are optional in C# function.
  In C#, a function is called by the function name.
  Let's learn function calling in the C# program.
  We call a function using function(method) name. In the example, we will create a function with parameters and also return type statement. This type of function is known as a parametrized function in C# programming.
  using System; namespace CircleApplication { class CirclePerimeter{ public double GetParimeter(double pai, double r) { /* local variable declaration */ double a; a=pai*r*r; //Find Area of circle using function return a; } static void Main(string[] args) { /* local variable definition */ double pai =3.14; double r= 2.5; double cir; CirclePerimeter obj= new CirclePerimeter(); //calling the GetParimeter function cir = obj.GetParimeter(pai, r); Console.WriteLine("Area of Circle : {0}", cir); Console.ReadLine(); } } }
  Output -
  Area of Circle : 19.625
  In the above C# example, we found area of the circle using the function call.
  In the previous C# constructor tutorial , we discussed defaults and parameterized constructor. In this tutorial, we are creating a function without a list of arguments and return type. In this C# example, we will use void as return type.
  If a function does not contain any list of argument(s) which is known as Non parameterized function
  using System; namespace TechnoSmarter { class Techno { double a; double b; double h; // User defined function without return type public void GetArea() // No Parameter { h =3.0; b=6.0; a=b*h/2; //Area of triangle Console.WriteLine("Area of triangle: "+a); // No return statement } // Main function, entry point static void Main(string[] args) { Techno triangle = new Techno(); // Creating Object triangle.GetArea(); // Calling Function GetArea() } } }
  Compiler and execute the above C# program. It gives the result as output.
  Output
  Area of triangle: 9
  In the above example, we create a function without any parameter and no return type in the C# program.