fclose - close a stream
#include <stdio.h>
int fclose(FILE *stream);
The fclose() function flushes the stream pointed to by stream (writing any buffered output data using fflush(3)) and closes the underlying file descriptor.
The behaviour of fclose() is undefined if the stream parameter is an illegal pointer, or is a descriptor already passed to a previous invocation of fclose().
Upon successful completion, 0 is returned. Otherwise, EOF is returned and errno is set to indicate the error. In either case, any further access (including another call to fclose()) to the stream results in undefined behavior.