Exception Types
There are a number of exception classes provided by C#, all of which inheritfrom the System.Exception class. Following are some common exception classes.
SystemException
A failed run-time check;used as a base class for other.
AccessException
Failure to access a type member, such as a method or field.
Failure to access a type member, such as a method or field.
ArgumentException
An argument to a method was invalid.
An argument to a method was invalid.
ArgumentNullException
A null argument was passed to a method that doesn't accept it.
A null argument was passed to a method that doesn't accept it.
ArgumentOutOfRangeException
Argument value is out of range.
Argument value is out of range.
ArithmeticException
Arithmetic over - or underflow has occurred.
Arithmetic over - or underflow has occurred.
ArrayTypeMismatchException
Attempt to store the wrong type of object in an array.
Attempt to store the wrong type of object in an array.
BadImageFormatException
Image is in the wrong format.
Image is in the wrong format.
CoreException
Base class for exceptions thrown by the runtime.
Base class for exceptions thrown by the runtime.
DivideByZeroException
An attempt was made to divide by zero.
An attempt was made to divide by zero.
FormatException
The format of an argument is wrong.
The format of an argument is wrong.
IndexOutOfRangeException
An array index is out of bounds.
An array index is out of bounds.
InvalidCastExpression
An attempt was made to cast to an invalid class.
An attempt was made to cast to an invalid class.
InvalidOperationException
A method was called at an invalid time.
A method was called at an invalid time.
MissingMemberException
An invalid version of a DLL was accessed.
An invalid version of a DLL was accessed.
NotFiniteNumberException
A number is not valid.
A number is not valid.
NotSupportedException
Indicates that a method is not implemented by a class.
Indicates that a method is not implemented by a class.
NullReferenceException
Attempt to use an unassigned reference.
Attempt to use an unassigned reference.
OutOfMemoryException
Not enough memory to continue execution.
Not enough memory to continue execution.
StackOverflowException
A stack has overflown.
A stack has overflown.
The finally block is used to do all the clean up code. It does not support
the error message, but all the code contained in the finally block is executed
after the exception is raised. We can use this block along with try-catch and
only with catch too.
The finally block is executed even if the error is raised. Control is always
passed to the finally block regardless of how the try blocks exits.
This is shown in the following example:
int a, b = 0 ;
Console.WriteLine( "My program starts" ) ;
try
{
a = 10 / b;
}
catch ( InvalidOperationException e )
{
Console.WriteLine ( e ) ;
}
catch ( DivideByZeroException e)
{
Console.WriteLine ( e ) ;
}
finally
{
Console.WriteLine ( "finally" ) ;
}
Console.WriteLine ( "Remaining program" ) ;
The output here is:
My program starts
System.DivideByZeroException: Attempted to divide by zero.
at ConsoleApplication4.Class1.Main(String[] args) in d:\programs\consoleapplication4\class1.cs:line
51
finally
Remaining program
But then what's the difference? We could have written
Console.WriteLine ("finally");
after the catch block, and not write the finally block at all. Writing finally
did not make much of a difference. Anyway the code written after catch gets executed.
The answer to this is not clear in this program. It will be clear when we see
the try-finally and the throw statement.
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