Exceptions in C#

When we write a program there are chances of coming across 2 different types of errors

• Compile-time Errors
• Run-time Errors.

An error which comes into picture at the time of program compilation is a compile-time error which may occur due to syntax mistakes. An error which occurs in the middle of the programs execution is known as a run-time error and these errors occur due to various reasons like wrong implementation of logic, wrong inputs supplied to a program, missing of required resources etc. 

A compile-time error is not dangerous because it occurs at the time of compilation whereas run-time errors are dangerous because they occur in the program when the execution is going on and if at all a run-time error occurs in a program, the program terminates abnormally on the same line where the error gets occured without executing the rest of the code.

Note:  Whenever an error situation occurs in a program the exception handler comes into picture to identify the type of error and then creates an object of an exception class associated with that error and throws that object and that object will first terminate the program abnormally and then displays an error message associated with an exception object.

Exception Handling

Whenever a run- time error occurs under the program abnormal termination is occuring so we will be facing so many problems in the application. To overcome the problems we are provided with a mechanism known as Exception Handling.

Exception Handling is a process of stopping the abnormal termination of the program whenever the exceptions are terminating the program in case of run time error. If we can stop the abnormal termination of a program we will be getting following advantages :

• We can make the statement which are not associated with the error.
• We can display a user friendly error message to the end user so that he can resolve the error, got occurred provided if it is in his hands.
• We can also perform some corrective actions to come out of a problems that may occur due to error.

To handle an exception we need to enclose our code under some special blocks known as try catch block which should be used as following:

try

{

-statements which requires execution when the run time error occurs.

-statements which does not require execution only when the run time error occurs.

}

catch

{

-statements which requires execution only when the run time error occurs.

}

[--< multiple catch blocks if required >--]

Add a class Exception demo.cs and write the following code:

using System;

namespace CSharpConsole
{
    class ExceptionDemo
    {
        static void Main()
        {
            int x, y, z;
            try
            {
                Console.WriteLine("Enter x value: ");
                x = int.Parse(Console.ReadLine());

                Console.WriteLine("Enter y value: ");
                y = int.Parse(Console.ReadLine());

                z = x / y;
                Console.WriteLine(z);
            }
            catch (DivideByZeroException ex1) //ex1 is a variable of class          DivideByZeroException
            {
                Console.WriteLine("Divisor must not be zero");
            }
            catch (FormatException ex2) //ex2 is a variable of class FormatException
            {
                Console.WriteLine("Input must be numeric");
            }

            catch (Exception ex3)
            {
                Console.WriteLine(ex3.Message);//message is a read only property
            }
            {
                Console.WriteLine("End of the program");
                Console.ReadLine();
            }
         }
    }
}