Category : C++ Source Code
Archive : VCCRT2.ZIP
Filename : UNGETC.C
Output of file : UNGETC.C contained in archive : VCCRT2.ZIP
*ungetc.c - unget a character from a stream
*
* Copyright (c) 1985-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines ungetc() - pushes a character back onto an input stream
*
*******************************************************************************/
#include
#include
#include
#include
#include
#include
/***
*int ungetc(ch, stream) - put a character back onto a stream
*
*Purpose:
* Guaranteed one char pushback on a stream as long as open for reading.
* More than one char pushback in a row is not guaranteed, and will fail
* if it follows an ungetc which pushed the first char in buffer. Failure
* causes return of EOF
*
*Entry:
* char ch - character to push back
* FILE *stream - stream to push character onto
*
*Exit:
* returns ch
* returns EOF if tried to push EOF, stream not opened for reading or
* or if we have already ungetc'd back to beginning of buffer.
*
*Exceptions:
*
*******************************************************************************/
int
ungetc (ch, str)
REG2 int ch;
FILE *str;
{
REG1 FILE _NEAR_ *stream;
assert(str != NULL);
/* Init stream pointer and file descriptor */
stream = (FILE _NEAR_ *) FP_OFF(str);
/* Stream must be open for read and can NOT be currently in write mode.
Also, ungetc() character cannot be EOF. */
if (
(ch == EOF) ||
!(
(stream->_flag & _IOREAD) ||
((stream->_flag & _IORW) && !(stream->_flag & _IOWRT))
)
)
return(EOF);
/* If stream is unbuffered, get one. */
if (stream->_base == NULL)
_getbuf(stream);
/* now we know _base != NULL; since file must be buffered */
if (stream->_ptr == stream->_base) {
if (stream->_cnt)
/* my back is against the wall; i've already done
* ungetc, and there's no room for this one
*/
return(EOF);
stream->_ptr++;
}
stream->_cnt++;
*--stream->_ptr = (char)ch;
stream->_flag &= ~_IOEOF;
stream->_flag |= _IOREAD; /* may already be set */
return(0xff & ch);
}
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/