ungetc(3p) [centos man page]

UNGETC(3P)						     POSIX Programmer's Manual							UNGETC(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       ungetc - push byte back into input stream

SYNOPSIS

       #include <stdio.h>

       int ungetc(int c, FILE *stream);

DESCRIPTION

       The ungetc() function shall push the byte specified by c (converted to an unsigned char) back onto the input stream pointed to  by  stream.
       The  pushed-back bytes shall be returned by subsequent reads on that stream in the reverse order of their pushing. A successful intervening
       call (with the stream pointed to by stream) to a file-positioning function ( fseek(), fsetpos(), or rewind()) shall discard any pushed-back
       bytes for the stream. The external storage corresponding to the stream shall be unchanged.

       One  byte of push-back shall be provided. If ungetc() is called too many times on the same stream without an intervening read or file-posi-
       tioning operation on that stream, the operation may fail.

       If the value of c equals that of the macro EOF, the operation shall fail and the input stream shall be left unchanged.

       A successful call to ungetc() shall clear the end-of-file indicator for the stream. The value of the file-position indicator for the stream
       after  reading or discarding all pushed-back bytes shall be the same as it was before the bytes were pushed back. The file-position indica-
       tor is decremented by each successful call to ungetc(); if its value was 0 before a call, its value is unspecified after the call.

RETURN VALUE

       Upon successful completion, ungetc() shall return the byte pushed back after conversion. Otherwise, it shall return EOF.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fseek(), getc(), fsetpos(), read(), rewind(), setbuf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								UNGETC(3P)

UNGETC(3P)						     POSIX Programmer's Manual							UNGETC(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       ungetc - push byte back into input stream

SYNOPSIS

       #include <stdio.h>

       int ungetc(int c, FILE *stream);

DESCRIPTION

       The ungetc() function shall push the byte specified by c (converted to an unsigned char) back onto the input stream pointed to  by  stream.
       The  pushed-back bytes shall be returned by subsequent reads on that stream in the reverse order of their pushing. A successful intervening
       call (with the stream pointed to by stream) to a file-positioning function ( fseek(), fsetpos(), or rewind()) shall discard any pushed-back
       bytes for the stream. The external storage corresponding to the stream shall be unchanged.

       One  byte of push-back shall be provided. If ungetc() is called too many times on the same stream without an intervening read or file-posi-
       tioning operation on that stream, the operation may fail.

       If the value of c equals that of the macro EOF, the operation shall fail and the input stream shall be left unchanged.

       A successful call to ungetc() shall clear the end-of-file indicator for the stream. The value of the file-position indicator for the stream
       after  reading or discarding all pushed-back bytes shall be the same as it was before the bytes were pushed back. The file-position indica-
       tor is decremented by each successful call to ungetc(); if its value was 0 before a call, its value is unspecified after the call.

RETURN VALUE

       Upon successful completion, ungetc() shall return the byte pushed back after conversion. Otherwise, it shall return EOF.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fseek(), getc(), fsetpos(), read(), rewind(), setbuf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								UNGETC(3P)