This is a file I/O function, also hardware dependent. It is not implemented in this Compiler.
#include <stdio.h>
int fflush(FILE *f);
fflush() flushes the I/O buffer of file f, allowing a clean switch between reading and writing the same file. If the program was writing to file f, fflush() writes all buffered data to the file. If it was reading, fflush() discards any buffered data. If f is NULL, fflush() flushes all files open for writing.
Zero, if no error occurred; EOF otherwise.