Conditional constructs

Conditional constructs

v  The various conditional constructs that can be included in a C# program are:

• The if…else construct
• The switch…case construct

The if…else construct

The if…else conditional construct is used to compare data and make decision on the basis of the result of the comparison.

For example, if you want to execute a piece of code, when the requirements meet then if… else construct determine which piece of code will be executed.

Else is default condition and executes when no if condition matches. The following example will clear the concept of if… else constructs.

Example

using System;

namespace if_else_construct

{

    class Program

    {

        static void Main(string[] args)

        {

            int opt, num1, num2;

            float result;

        label:

            Console.WriteLine("\n\tMenu");

            Console.WriteLine("\nPress 1 for add");

            Console.WriteLine("Press 2 for subtraction");

            Console.WriteLine("Press 3 for multiplication");

            Console.WriteLine("Press 4 for Division");

            Console.Write("\n\nEnter first number:\t");

            num1 = Convert.ToInt32(Console.ReadLine());

            Console.Write("Enter second number:\t");

            num2 = Convert.ToInt32(Console.ReadLine());

            Console.Write("\nEnter your option:\t");

            opt = Convert.ToInt32(Console.ReadLine());

            if (opt==1)

            {

               result = num1 num2;

               Console.WriteLine("\n{0}+{1}={2}",num1,num2,result);

            }

            else if (opt==2)

            {

               result = num1 - num2;

               Console.WriteLine("\n{0}-{1}={2}",num1,num2,result);

            }

            else if (opt==3)

            {

               result = num1 * num2;

               Console.WriteLine("\n{0}x{1}={2}",num1,num2,result);

            }

            else if (opt==4)

            {

               result = (float)(num1 / num2);

               Console.WriteLine("\n{0}/{1}={2}",num1,num2,result);

            }

            else

            {

               Console.WriteLine("Invalid option. Try again");

               goto label;

            }

            Console.ReadLine();

        }

    }

}

The switch…case construct

The switch…case construct is used when you want to compare the value of a variable with multiple values.

Example

using System;
 
namespace Switch_Case
{
  class Program
   {
     static void Main(string[] args)
      {
        int opt, num1, num2;
        float result;
 
        label:
 
        Console.WriteLine("\n\tMenu");
        Console.WriteLine("\nPress 1 for add");
        Console.WriteLine("Press 2 for subtraction");
        Console.WriteLine("Press 3 for multiplication");
        Console.WriteLine("Press 4 for Division");
  
        Console.Write("\n\nEnter first number:\t");
        num1 = Convert.ToInt32(Console.ReadLine());
 
        Console.Write("Enter second number:\t");
        num2 = Convert.ToInt32(Console.ReadLine());
 
        Console.Write("\nEnter your option:\t");
        opt = Convert.ToInt32(Console.ReadLine());
 
        switch (opt)
         {
           case 1:

              result = num1 + num2;
              Console.WriteLine("\n{0}+{1}={2}",num1,num2,result);
              break;
 
              case 2:
              result = num1 - num2;
              Console.WriteLine("\n{0}-{1}={2}",num1,num2,result);
              break;
              case 3:
              result = num1 * num2;
              Console.WriteLine("\n{0}*{1}={2}",num1,num2,result);
              break;
              case 4:
              result =(float)num1 / num2;
              Console.WriteLine("\n{0}/{1}={2}",num1,num2,result);
              break;
              default:
               Console.WriteLine("\nInvalid option.Please tryagain.");
                goto label;
         }
        Console.ReadLine();
      }
   }
}