C# : Switch Case With When

In C#, Switch - Case statement is just alternative of IF-ELSE statement and it allows a variable to be equality compared against list of case values.

Example :

     string colorCode = "R";

            string Color = string.Empty;

            switch (colorCode)

            {

                case "R":

                    Color = "RED";

                    break;

                case "B":

                    Color = "BLUE";

                    break;

                case "Y":

                    Color = "YELLOW";

                    break;

                default:

                    Color = "UNKNOWN";

                    break;

            }
           
            Console.WriteLine(Color);
          
Output :
                RED  

but It is a very simple equality check , if you want to perform greater, less than or range pattern matching. It will not help you let’s see a real problem.

Problem:  Show student examination result based on student mark:

Mark < 32: Failed

Mark >=32 AND Mark <= 45: 3^rd Grade

Mark > 45 AND Mark <= 60: 2^nd Grade

Mark > 60: 1^st Grade

In C# 7.0, C# introduce new Case-When Clause, where you can apply additional condition on that.

            int mark = 34;

            string ExamResult = string.Empty;

            switch (mark)

            {

                case int m when (m < 32):

                    ExamResult = "FAILED";

                    break;

               case int m when (m >= 32 && m <= 45):

                    ExamResult = "3rd Grade";

                    break;

                case int m when (m > 45 && m <= 60):

                    ExamResult = "2nd Grade";

                    break;

               case int m when (m > 60):

                    ExamResult = "1st Grade";

                    break;

                default:

                    ExamResult = "InValid";

                    break;

            }

                      Console.WriteLine(ExamResult);

Output :
                3rd Grade

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