Exceptions Handling in C# - Error handling in c# with example

Exception Handling in C#: An Overview

Errors refer to the mistakes or faults that occur during program development or execution. If you don't find them and correct them, they cause a program to produce wrong results. In this C# Tutorial, we will explore more about Errors and Exceptions which will include exception handling in c#, types of errors in c#, try-catch-finally blocks in c#,and last proper use of try-catch, and finally block.

Types of Error Handling in C#

In programming language, errors can be divided into three categories as given below-

1. Syntax Errors

Syntax errors occur during development when you make type mistakes in code. For example, instead of writing while you write WHILE then it will be a syntax error since C# is a case-sensitive language.

1.  bool flag=true;
   
   WHILE (flag) //syntax error, since c# is case sensitive
   {
    //TO DO:
   }

2. Runtime Errors (Exceptions)

Runtime errors, also called exceptions, occur during the program's execution and can be caused by improper user inputs, improper design logic, or system errors.

1.  int a = 5, b = 0;
   int result = a / b; // DivideByZeroException
   

Exceptions can be handled by using try-catch blocks.

3. Logical Errors

Logic errors occur when the program is written fine but does not produce the desired result. Logic errors are difficult to find because you need to know for sure that the result is wrong

1. 1. int a = 5, b = 6; double avg = a + b / 2.0; // logical error, it should be (a + b) / 2.0

Read More - C# Programming Interview Questions

Exception Handling In C#

Exception handling is a mechanism for detecting and handling run-time errors. It is achieved by using the Try-Catch-Finally blocks and the throw keyword.

1. Try block

The try block encloses the statements that might throw an exception.

1.  try
   {
    // Statements that can cause exception.
   }
    

2. Catch block

1. Catch block handles any exception if one exists.

    catch(ExceptionType e)
   {
    // Statements to handle exception.
   }

3. Finally, block

1. The finally block can be used for doing any clean-up process like releasing unused resources even if an exception is thrown. For example, disposing database connection.

    finally
   {
    // Statement to clean up.
   }

4. Throw keyword

1. This keyword is used to throw an exception explicitly.

    catch (Exception e)
   {
    throw (e);
   }  

Key points about exception handling

1. Exceptions are types that all directly or indirectly derive from the System. Exception class.

2. Exception objects contain detailed information about the error, such as the state of the call stack and a text description of the error.

3. A try block is used to throw multiple exceptions that can be handled by using multiple catch blocks.

4. A more specialized catch block should be executed before a generalized one. Otherwise, the specialized catch block will never be executed.

5. Exceptions can be explicitly generated by a program by using the throw keyword.

6. If no exception-handling mechanism is used, the program stops executing with an error message.

7. By providing a catch block without brackets or arguments, we can catch all exceptions that occur inside a try block.

    Catch
   {
    Console.WriteLine("oException" );
   } 

8. By providing a catch block with an exception object, you can obtain more information about the type of exception that occurred.

    catch(Exception e)
   {
    Console.WriteLine(e.Message);
   }
   

9. The statements inside the finally block are always executed whether an exception occurs or not in the program.

10. Also, before the termination of the program finally block is always executed.

Order of Try-Catch-Finally blocks

In the order of exception handling, blocks try block comes first, after that, catch block(s) comes, and the last final block comes. Let's see in C# Compiler.

 try
{
 // statements that can cause exception.
}
catch (MoreSpecificExceptionType e1)
{
 // error handling code
}
catch (SpecificExceptionType e2)
{
 // error handling code
}
catch (GeneralExceptionType eN)
{
 // error handling code
}
finally
{
 // statement to clean up.
} 

You can also skip finally block if required.

 try
{
 // statements that can cause exception.
}
catch (MoreSpecificExceptionType e1)
{
 // error handling code
}
catch (SpecificExceptionType e2)
{
 // error handling code
}
catch (GeneralExceptionType eN)
{
 // error handling code
} 
  

You can also skip catch block(s) if required.

 try
{
 // statements that can cause exception.
}
finally
{
 // statement to clean up.
}

Hence, a combination of try-catch-finally or try-catch or try-finally blocks is valid.

List of C# Exceptions :

Conclusion

I hope you will enjoy handling exceptions in C# while programming. I would like feedback from my blog readers. Your valuable feedback, questions, or comments about this article are always welcome. Also, Consider our C# Programming Course for a better understanding of all C# concepts.

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