The exception classes forma hierarchy with
CException
as the base class.
CException provides a unified interface
to all exceptions that allow you to get human readable messages
and status information that can be processed by computers (e.g.
for exception recovery).
All exceptions have the following member functions (virtual):
virtual const const char* ReasonText();
Which returns a human readable error string that contains an error
message describing why the exception was thrown and what was being done
when the error that triggered the exception occured.
virtual const Int_t ReasonCode();
Which returns some exception specific error code, that
can be processed by software for error recovery.
The example below shows the simplest handling of
CException types. Note that the exception
is caught by reference so that member functions retain their
polymorphism.
Example 42-1. Catching CException and exiting
#include <Exception.h>
#include <iostream>
using namespace std;
...
try {
...
}
catch (CException& error) {
cerr << err.ReasonText() << endl;
exit(-1);
}
The example prints out a meaningful error message and exits the program.