The difference between FILE* and FD

Obviously using fopen, fwrite etc... is a little bit easier especially since you don't have to keep track of the location in the stream, using plain old open, write etc.. also have their uses.

Consider this.. I want to write a test case which writes to a file over and over again. The idea is to write x bytes to the file, seek to 0, and repeat.

Problem is that this will not work when you use FILE pointers. It will work most times, except when the file itself has to be created. In which case, using seek to 0 does nothing, because every fwrite will automatically seek to the end of the file. So, fopen a new file will always open it in append mode.