ungetc(3) BSD Library Functions Manual ungetc(3)
ungetc -- un-get character from input stream
Standard C Library (libc, -lc)
#include <stdio.h> int ungetc(int c, FILE *stream);
The ungetc() function pushes the character c (converted to an unsigned char) back onto the input stream pointed to by stream. The pushed-back characters will be returned (in reverse order) by subsequent reads on the stream. A successful intervening call to one of the file positioning functions (fseek(3), fsetpos(3), or rewind(3)), using the same stream, will discard the pushed-back characters. Only one character of push-back is guaranteed, but as long as there is sufficient memory, an effectively infinite amount of push-back is allowed. If a character is successfully pushed-back, the end-of-file indicator for the stream is cleared. The file-position indicator is decremented by each successful call to ungetc(); if its value was 0 before a call, its value is unspecified after the call.
The ungetc() function returns the character pushed-back after the conver- sion, or EOF if the operation fails. If the value of the argument c character equals EOF, the operation will fail and the stream will remain unchanged.
The ungetc() function conforms to ISO/IEC 9899:1990 (``ISO C90''). BSD June 4, 1993 BSD
Mac OS X 10.8 - Generated Fri Aug 31 16:53:58 CDT 2012