Lets say I'm trying to write to a file and the operation of doing this fails. Wouldn't I have to write additional code to make sure every outcome of my code was successful ,make sure data was written to the said file? If an error is not checked the application will just go on running code. An error is only an error if it is defined as one, otherwise the CPU continues running the code with erroneous data.
An analogy would be checking a simple mathematical addition equation by subtracting one of the addends from the sum to see if the other addend was left. If this check is not made we are not aware of the error and computations using this faulty data continue.
This webpage gives my original post some structure
http://wiki.webratio.com/index.php/Debugging_with_application's_logs
I got to this topic indirectly from ELF files so that won't help much. Let's say I'm writing an application and think it will be useful to have some log files to view so when it crashes I will have a clue of what to look at to solve the problems the application is experiencing.