ungetc(3S)

ungetc -- push character back onto input stream

Synopsis

   #include <stdio.h>
   
   int ungetc (int c, FILE stream);

Description

ungetc inserts the character specified by c (converted to an unsigned char) into the buffer associated with an input stream [see intro(3)]. That character, c, will be returned by the next getc(3S) call on that stream. ungetc returns c, and leaves the file corresponding to stream unchanged. A successful call to ungetc clears the EOF indicator for stream.

The value of the file position indicator for stream after reading or discarding all pushed-back characters will be the same as it was before the characters were pushed back.

If c equals EOF, ungetc does nothing to the buffer and returns EOF.

fseek, rewind [both described on fseek(3S)], and fsetpos erase the memory of inserted characters for the stream on which they are applied.

Errors

ungetc returns EOF if it cannot insert the character.

References

fseek(3S), fsetpos(3C), getc(3S), Intro(3S), setbuf(3S)