C# 0 The Complete Reference

try

 block is 

put in a 

finally

 block.

Using try and catch

At the core of exception handling are 

try

 and 

catch

. These keywords work together, and you 

can’t have a 

catch

 without a 

try

. Here is the general form of the 

try

/

catch

 exception-handling 

blocks:

try {

   // block of code to monitor for errors

}

catch (

ExcepType1 exOb

) {

   // handler for 

ExcepType1

}

catch (

ExcepType2 exOb

) {

   // handler for 

ExcepType2

}

.

.

.

Here, 

ExcepType

 is the type of exception that has occurred. When an exception is thrown, 

it is caught by its corresponding 

catch

 clause, which then processes the exception. As the 

general form shows, more than one 

catch

 clause can be associated with a 

try

. The type of 

the exception determines which 

catch

 is executed. That is, if the exception type specified 

by a 

catch

 matches that of the exception, then that 

catch

 is executed (and all others are 

bypassed). When an exception is caught, the exception variable 

exOb

 will receive its value.

Actually, specifying 

exOb

 is optional. If the exception handler does not need access to the 

exception object (as is often the case), there is no need to specify 

exOb.

 The exception type 

alone is sufficient. For this reason, many of the examples in this chapter will not specify 

exOb.

Here is an important point: If no exception is thrown, then a 

try

 block ends normally, 

and all of its 

catch

 clauses are bypassed. Execution resumes with the first statement 

following the last 

catch

. Thus, a 

catch

 is executed only if an exception is thrown.

A Simple Exception Example

Here is a simple example that illustrates how to watch for and catch an exception. As you 

know, it is an error to attempt to index an array beyond its boundaries. When this error 

occurs, the CLR throws an 

IndexOutOfRangeException

, which is a standard exception 

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