C# System Exception
In this chapter you will learn:
- What is C# System Exception
- Common Exception Types
- Use the NullReferenceException
- Use ArgumentNullException
- Use OverflowException
- Use DivideByZeroException
Description
The most important properties of System.Exception are the following:
- StackTrace - A string representing all the methods that are called from the origin of the exception to the catch block.
- Message - A string with a description of the error.
- InnerException - The inner exception (if any) that caused the outer exception. This, itself, may have another InnerException.
Common Exception Types
| 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.
Example
using System; //from w ww . j a v a2s . co 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.
Example 2
using System;/*from w ww .ja va2s . com*/
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.
Exception 3
The following code
checks OverflowException for long.
using System;// w w w . j ava 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);
}
}
}
The code above generates the following result.
Example 4
Define exception variable in catch statement: DivideByZeroException.
using System;//www . ja v 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.
Next chapter...
What you will learn in the next chapter: