_ungetch, _ungetwch
Visual Studio .NET 2003
Pushes back the last character read from the console.
int _ungetch( int c ); wint_t _ungetwch( wint_t c );
Parameter
- c
- Character to be pushed.
Return Value
Both functions return the character c if successful. If there is an error, _ungetch returns a value of EOF and _ungetwch returns WEOF.
Remarks
These function push the character c back to the console, causing c to be the next character read by _getch or _getche (or _getwch or _getwche). _ungetch and _ungetwch fail if they are called more than once before the next read. The c argument may not be EOF (or WEOF).
Generic-Text Routine Mappings
| TCHAR.H routine | _UNICODE & _MBCS not defined | _MBCS defined | _UNICODE defined |
|---|---|---|---|
| _ungettch | _ungetch | _ungetch | _ungetwch |
Requirements
| Routine | Required header | Compatibility |
|---|---|---|
| _ungetch | <conio.h> | Win 98, Win Me, Win NT, Win 2000, Win XP |
| _ungetch | <conio.h> or <wchar.h> | Win 98, Win Me, Win NT, Win 2000, Win XP |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
All versions of the C run-time libraries.
Example
// crt_ungetch.c
// compile with: /c
/* In this program, a white-space delimited
* token is read from the keyboard. When the program
* encounters a delimiter, it uses _ungetch to replace
* the character in the keyboard buffer.
*/
#include <conio.h>
#include <ctype.h>
#include <stdio.h>
int main( void )
{
char buffer[100];
int count = 0;
int ch;
ch = _getche();
while( isspace( ch ) ) /* Skip preceding white space. */
ch = _getche();
while( count < 99 ) /* Gather token. */
{
if( isspace( ch ) ) /* End of token. */
break;
buffer[count++] = (char)ch;
ch = _getche();
}
_ungetch( ch ); /* Put back delimiter. */
buffer[count] = '\0'; /* Null terminate the token. */
printf( "\ntoken = %s\n", buffer );
}
Input
White
Output
token = White
See Also
Console and Port I/O Routines | _cscanf | _getch | Run-Time Routines and .NET Framework Equivalents
