_ungetch - Push Character Back to Keyboard

Syntax

#include <conio.h>
int _ungetch(int c);

ungetch pushes the character c back to the keyboard, causing c to be the next character read. _ungetch fails if called more than once before the next read operation. The character c cannot be the EOF character.

If successful, _ungetch returns the character c. A return value of EOF indicates an error.

This example uses _getch to read a string delimited by the character 'x'. It then calls _ungetch to return the delimiter to the keyboard buffer. Other input routines can then process the delimiter.

#include <conio.h>
#include <stdio.h>

int main(void)
{
   int ch;

   printf("Type in some letters.\n");
   printf("If you type in an 'x', the program ends.\n");
   for (; ; ) {
      ch = _getch();
      if ('x' == ch) {
         _ungetch(ch);
         break;
      }
      _putch(ch);
   }
   ch = _getch();
   printf("\nThe last character was '%c'.", ch);
   return 0;

   /****************************************************************************
      Here is the output from a sample run:

      Type in some letters.
      If you type in an 'x', the program ends.
      One Two Three Four Five Si
      The last character was 'x'.
   ****************************************************************************/
}

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