Outputs the stream input/output file buffer contents to the file.

[Format]

#include <stdio.h>

long fflush (FILE *fp);

[Parameters]

fp File pointer

[Return values]

Normal: 0

Abnormal: Nonzero

[Remarks]

When the output file of the stream input/output file is open, the fflush function outputs the contents of the buffer that is not output for the stream input/output file specified by file pointer fp to the file. When the input file is open, the ungetc function specification is invalidated.