HOW TO CREATE USER DEFINED EXCEPTION ?

Abhishek Srivasatava

Total Post:70

Points:350
Posted by  Abhishek Srivasatava
C#
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  1. Abhishek Srivasatava

    Post:70

    Points:350
    How to create user defined Exception ?


    Following is the step we need to follow to create user defined exception:

    Step 1 : Create a derived class and inherit it with exception base class

    example // class universalerror : Exception


    Step 2 :  create a constructor for the derived class and pass the string parameter 

     syntax : public universalerror(String message) : base(message) // what is the need  of this line. I will explain you through  program in 3 step.


    step 3  : Declaration for the exception is made by the above two steps. Now we need to define the exception.             

                 Create another class under the new class create a function put the condition for this variable

    example :
    class testexp
        {
            public int a;
     
            public void strgerr()
            {
                if (a== 0)
                {
                    throw (new universalerror("Error, please check")); // Base Message when exception is meet
               
                }
                else
                {
                    Console.WriteLine("Universal error is not there");// Base Message when exception is not meet.           
                }
            }
        }

    Base message in step : 2 is to give the add on for the string message (which may   define in the main program or in executing function).

    step 4 :  Now create another class , create the object for the defining class of the exception .


    Step 5: now with the help of three keyword Try & Catch


    class Program
        {
     
            static void Main(string[] args)
            {
              
                testexp exp1 = new testexp();
                try
                { exp1.a = 25;
                    exp1.strgerr();
                }
                catch (universalerror e)
                {  Console.WriteLine("universal error {0}", e.Message);
                }
                Console.ReadLine();
            }
        }
    }
     

    Under Try : we perform all operations.

    Under Catch :  if an exception is met , then we can give the add on to the defined message .


    Here is the complete program for the above step:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    namespace ConsoleApplication3
    {
        classuniversalerror : Exception
        {
            public universalerror(String message) : base(message)
            {
            }
        }
        class testexp
        {
            public int a;
            public void strgerr()
            {
                if (a== 0)
                {  throw (new universalerror("Error, please check"));          
                }
                else
                {   Console.WriteLine("Universal error is not there");       
                }
            }
        }
        class Program
        {
            static void Main(string[] args)
            {       
                testexp exp1 = new testexp();
                try
                {
                    exp1.a = 0; //for exception is met.
    //exp1.a=25; for exception is not met.
                    exp1.strgerr();         
                }
                catch (universalerror e)
                { Console.WriteLine( "universal error {0}",e.Message);
                }
                Console.ReadLine();
            }
        }
    }

      Modified On Sep-25-2016 11:38:45 PM

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