Functions HI-TECH C UNGETC
#include <stdio.h> int ungetc(int c, FILE * stream)
Ungetc() will attempt to push back the character c onto the named stream, such that a subsequent getc() operation will return the character. At most one level of pushback will be allowed, and if the stream is not buffered, even this may not be possible. EOF is returned if the ungetc() could not be performed.