C# Tutorial - Application 5 – Refactoring

Create a new console Application called App05. We are going to simplify the previous application by adding a method. The method is being added because we have some code that is very similar except for variable names. Duplicated code should be turned into a method to allow ease of maintainability.

1. Highlight the code from the label first: through to the end of the catch statement.
2. Right-click over the highlighted code and select Refactor.
3. Now select Extract Method.
4. In the dialog box that appears, choose a name for the new method such as GetNumber.
   
   
   
   
   
5. The method signature needs a slight tweak for what we want. Delete the parameter.
6. Now add a local variable in the method, so that the code looks like the following.
   
   

   Using System;
   
   class Program
   {
     static void Main(string[] args)
     {
       // Storage
       int value1 = 0;
       int value2 = 0;
       int total = 0;
   
       // Get first number
       value1 = GetNumber();
   
       // Get second number
       value2 = GetNumber();
   
       // Add them together
       total = value1 + value2;
   
       // Output the answer
       Console.WriteLine("The total is {0}", total);
     }
   
     // Get each number
     private static int GetNumber()
     {
       int i = 0;
       first:
       try
       {
         Console.Write("Enter a whole number: ");
         i = System.Convert.ToInt32(Console.ReadLine());
       }
       catch (System.ArgumentNullException)
       {
         Console.WriteLine("String is null.");
         goto first;
       }
       catch (System.FormatException)
       {
         Console.WriteLine("String does not consist of an " +
             "optional sign followed by a series of numbers.");
         goto first;
       }
       catch (System.OverflowException)
       {
         Console.WriteLine("Overflow in string to int conversion.");
         goto first;
       }
       return i;
     }
   }