System exception

In this chapter you will learn:

Commonly Used Exceptions Defined Within the System Namespace
Use the NullReferenceException
Use ArgumentNullException
Use OverflowException
Use DivideByZeroException

Commonly Used Exceptions Defined Within the System Namespace

Exception	Meaning
ArrayTypeMismatchException	Type is incompatible with the type of the array.
DivideByZeroException	Division by zero attempted.
IndexOutOfRangeException	Array index is out of bounds.
InvalidCastException	A runtime cast is invalid.
OutOfMemoryException	Insufficient free memory exists.
OverflowException	An arithmetic overflow occurred.
NullReferenceException	An attempt was made to operate on a null reference?that is, a reference that does not refer to an object.
StackOverflowException	The stack was Overflow.

As a general rule, exceptions defined by you should be derived from ApplicationException since this is the hierarchy reserved for application- related exceptions.

Use the NullReferenceException

using System;  //from   j  ava2 s. c  o  m
  
class MainClass {   
  public static void Main() {   

    try { 
      string str = null;
      Console.WriteLine(str.ToString());
      
    } catch (NullReferenceException) { 
      Console.WriteLine("NullReferenceException!"); 
      Console.WriteLine("fixing...\n"); 
 
    } 
 
  }  
}

The code above generates the following result.

ArgumentNullException

using System;/*j ava2s  .c o m*/

class MainClass
{
   static void Main()
   {
      string arg = null;
      
      try
      {
         if (arg == null)
         {
            ArgumentNullException MyEx = new ArgumentNullException();
            throw MyEx;
         }
      }
      catch (ArgumentNullException e)
      {
         Console.WriteLine("Message: {0}", e.Message);
      }
   }
}

The code above generates the following result.

OverflowException

The following code checks OverflowException for long.

using System;//  ja va 2  s.c o  m

class MainClass
{
  static void Main(string[] args)
  {
    int MyInt = 12345000;
    long MyLong = MyInt;
    
    try
    {
      long c = checked(MyLong * 5000000);
    }
    catch (OverflowException e)
    {
      Console.WriteLine(e);
    }

  }

}

DivideByZeroException

Define exception variable in catch statement: DivideByZeroException

using System;// j  av a  2 s  .co m

class MainClass
{
   static void Main()
   {
      try
      {
         int y = 0;
         y = 10/y; 
      } catch (DivideByZeroException e) {
         Console.WriteLine("Message: {0}", e.Message);
         Console.WriteLine("Source: {0}", e.Source);
         Console.WriteLine("Stack: {0}", e.StackTrace);
      }
   }
}

The code above generates the following result.

System exception

Commonly Used Exceptions Defined Within the System Namespace

Use the NullReferenceException

ArgumentNullException

OverflowException

DivideByZeroException

Next chapter...

Exception

Exception classes

try...catch

catch exceptions

finally

throw exception

System exception

User-Defined Exception Classes