Debugging is closely associated with testing and editing. Debugging involves determining why a behavior occurs and how to change it. Traditional debugging includes one of these options to determine what is occurring:
Console.Writeln() statements are interspersed with regular code
Debug functions are interspersed with regular code
In the first option, the code must be removed after the problem is located. In the second option, the code can stay, because debug functions can be turned on and off providing permanent instrumentation. While the second option is the better option, both have the disadvantage that manual instrumentation is not flexible, and is used only when identifying a specific situation that was anticipated by the programmer when the code was originally written.