clears the buffers of the given stream.
For output streams this discards any unwritten output.
For input streams this discards any input read from the underlying object
but not yet obtained via
this includes any text pushed back via
does precisely the same, but without returning a value.
Upon successful completion
On error, it returns -1 and sets
is not an open stream.
These functions are nonstandard and not portable.
was introduced in 4.4BSD and is not available under Linux.
was introduced in Solaris, and is present in glibc 2.1.95 and later.
Usually it is a mistake to want to discard input buffers.