Assertions are used to handle errors that should never occur in the code. How do you handle errors that you do expect to occur? Depending on the specific circumstances, you might want to return a neutral value, substitute the next piece of valid data, return the same answer as the previous time, substitute the closest legal value, log a warning message to a file, return an error code, call an error-processing routine or object, display an error message, or shut down—or you might want to use a combination of these responses.
Here are some more details on these options:
Return a neutral value. Sometimes the best response to bad data is to continue operating and simply return a value that's known to be harmless. A numeric ...