The following two functions provide information about the output buffer
of a FILE * stream.
The fpending function returns
the number of pending (a.k.a. buffered, unflushed) bytes in the given stream.
The fbufmode function returns the buffering mode of the given stream:
| Result | means |
|---|---|
_IONBF | unbuffered |
_IOLBF | line buffered |
_IOFBF | fully buffered |
Note that on some platforms,
it is impossible to distinguish _IOFBF and _IOLBF.