1.12.5 <stdio.h>: Direct Input and Output

size_t fread(void *ptr, size_t size, size_t nobj, FILE *stream)

fread reads from stream into the array ptr at most nobj objects of size size.  fread returns the number of objects read; this may be less than the number requested.  feof and ferror must be used to determine status.

size_t fwrite(const void *ptr, size_t size, size_t nobj, FILE *stream)

fwrite writes, from the array ptr, nobj objects of size size on stream.  It returns the number of objects written, which is less than nobj on error.