Using the C++ Math Library

Replacing the Default Library Error Handler

The default error handling behavior of the MATLAB C++ Math Library routines is implemented by the default library error handler routine. You can customize error handling by replacing the default library error handler routine with one of your own design.

Note    If your compiler supports exceptions, the error handler is only called for warning-level errors. For all other errors, a C++ exception is thrown.

To replace the default error handler you must:

• Write an error handler
• Register your error handler so that library routines call it when they encounter an error

Writing an Error Handler

When you write an error handler, you must conform to the library prototype for error handling routines:

void MyErrorHandler( const char *msg, bool isError  )
{
    if(isError) // Will always be false if exceptions supported
    {
       // Process Error 
    }
     else
    {
       // Process Warning
    }
}

In this prototype, note the following:

• An error handling routine must not return a value (return void).
• An error handling routine accepts two arguments, a const string and a Boolean value. The string is the text of the error message. When the value of this Boolean value is TRUE, it indicates an error message. If this value is FALSE, it indicates a warning message.

Registering Your Error Handler

After writing an error handler, you must register it with the MATLAB C Math Library so that the library routines can call it when they encounter an error condition at runtime. You register an error handler using the mwSetErrorMsgHandler() routine.

mwSetErrorMsgHandler(MyErrorHandler);

Example Program: Handling Exceptions (ex5.cpp)

Exception Handling in the MATLAB C++ Math Library