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cfile-descriptorfile-pointer

What's the difference between a file descriptor and a file pointer?

How are file descriptors and file pointers related? When is it appropriate to use each?

Solution

  • A file descriptor is a low-level integer "handle" used to identify an opened file (or socket, or whatever) at the kernel level, in Linux and other Unix-like systems.

    You pass "naked" file descriptors to actual Unix calls, such as read(), write() and so on.

    A FILE pointer is a C standard library-level construct, used to represent a file. The FILE wraps the file descriptor, and adds buffering and other features to make I/O easier.

    You pass FILE pointers to standard C functions such as fread() and fwrite().