What's the difference between using the functions fgetpos() and fsetpos() and using the functions ftell() and fseek() to get and set a position in a file?
What are fgetpos() and fsetpos() good for? Why would they be used instead of ftell() and fseek()?
Well, from the manpage we can see that ftell and fseek use type long int to represent offsets (positions) in a file, and may therefore be limited to offsets which can be represented in a long int. (Type long int is not guaranteed to hold values larger than 2**31-1, limiting the maximum offset to 2 gigabytes). The newer fgetpos and fsetpos functions, on the other hand, use a special typedef, fpos_t, to represent the offsets. The type behind this typedef, if chosen appropriately, can represent arbitrarily large offsets, so fgetpos and fsetpos can be used with arbitrarily huge files. fgetpos and fsetpos also record the state associated with multibyte streams.