Switch statement

Switch statement
 A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each switch case. or we can say  switch statement allows you to choose from many statements based on multiple selections by passing control to one of the case statements within its body. The switch statement executes the case corresponding to the value of the expression . The switch statement can include any number of case instances.

Syntax:
switch(expression) {
   case constant-expression  :
      statement(s);
      break; /* optional */
   case constant-expression  :
      statement(s);
      break; /* optional */
 
   /* you can have any number of case statements */
   default : /* Optional */
   statement(s);
}



The following rules apply to a switch statement:
The expression used in a switch statement must have an integral or enumerated type, or be of a class type in which the class has a single conversion function to an integral or enumerated type.
 
You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon.
 
The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal.
 
When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.

 When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.

 Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached.
 
 A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.
For Example:

using System;

class Program
{
    static void Main(string[] args)
    {
        /* local variable definition */

        Start: Console.WriteLine("Enter your grade");
    
        char grade = Convert.ToChar(Console.ReadLine());
        //char grade = 'B';

        switch (grade)
        {
            case 'A':
                Console.WriteLine("Excellent!");
                break;
            case 'B':
            case 'C':
                Console.WriteLine("Well done");
                break;
            case 'D':
                Console.WriteLine("You passed");
                break;
            case 'F':
                Console.WriteLine("Better try again");
                break;
            default:
                Console.WriteLine("Invalid grade");
                break;
               
        }
        Console.WriteLine("Your grade is  {0}", grade);       
        Console.ReadLine();
        goto Start;
    }
}

When the above code is compiled and executed, it produces the following result:

 







For Example:
using System;
class Program
{
    static void Main()
    {
        while (true)
        {
            System.Console.WriteLine("Type number and press Return");
            try
            {
                int i = int.Parse(System.Console.ReadLine());
                switch (i)
                {
                    case 0:
                    case 1:
                    case 2:
                        {
                            System.Console.WriteLine("Low number");
                            break;
                        }
                    case 3:
                    case 4:
                    case 5:
                        {
                            System.Console.WriteLine("Medium number");
                            break;
                        }
                    default:
                        {
                            System.Console.WriteLine("Other number");
                            break;

                        }
                }
            }
            catch
            {
            }
        }
    }
}
When the above code is compiled and executed, it produces the following result: