Exception Processing

When a program executes, a number of abnormal conditions and errors called "exceptions" can occur. These may include running out of memory, resource allocation errors, and failure to find files.

The Microsoft Foundation Class Library uses an exception-handling scheme that is modeled closely after the one proposed by the ANSI standards committee for C++. An exception handler must be set up before calling a function that may encounter an abnormal situation. If the function encounters an abnormal condition, it throws an exception and control is passed to the exception handler.

Several macros included with the Microsoft Foundation Class Library will set up exception handlers. A number of other global functions help to throw specialized exceptions and terminate programs, if necessary. These macros and global functions fall into the following categories:

• Exception macros, which structure your exception handler.

• Exception-throwing functions, which generate exceptions of specific types.

• Termination functions, which cause program termination.

For examples and more details, see the article Exceptions.

Exception Macros

TRY	Designates a block of code for exception processing.
CATCH	Designates a block of code for catching an exception from the preceding TRY block.
CATCH_ALL	Designates a block of code for catching all exceptions from the preceding TRY block.
AND_CATCH	Designates a block of code for catching additional exception types from the preceding TRY block.
AND_CATCH_ALL	Designates a block of code for catching all other additional exception types thrown in a preceding TRY block.
END_CATCH	Ends the last CATCH or AND_CATCH code block.
END_CATCH_ALL	Ends the last CATCH_ALL code block.
THROW	Throws a specified exception.
THROW_LAST	Throws the currently handled exception to the next outer handler.

Exception-Throwing Functions

AfxThrowArchiveException	Throws an archive exception.
AfxThrowFileException	Throws a file exception.
AfxThrowMemoryException	Throws a memory exception.
AfxThrowNotSupportedException	Throws a not-supported exception.
AfxThrowResourceException	Throws a Windows resource-not-found exception.
AfxThrowUserException	Throws an exception in a user-initiated program action.

MFC provides two exception-throwing functions specifically for OLE exceptions:

OLE Exception Functions

AfxThrowOleDispatchException	Throws an exception within an OLE automation function.
AfxThrowOleException	Throws an OLE exception.

To support database exceptions, the database classes provide two exception classes, CDBException and CDaoException, and global functions to support the exception types:

DAO Exception Functions

AfxThrowDAOException	Throws a CDaoException from your own code.
AfxThrowDBException	Throws a CDBException from your own code.

MFC provides the following termination function:

Termination Functions

AfxAbort

Called to terminate an application when a fatal error occurs.

See Also

Reference

CException Class

Concepts

MFC Macros and Globals