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ungetch

Header File 

conio.h 

Category 

Console I/O Routines 

Prototype 

int ungetch(int ch); 

Description 

Pushes a character back to the keyboard buffer.

Note: Do not use this function in Win32 GUI applications.
ungetch pushes the character ch back to the console, causing ch to be the next character read. The ungetch function fails if it is called more than once before the next read. 

Return Value 

On success, ungetch returns the character ch. 

On error, it returns EOF. 

Example  

#include <stdio.h>
#include <ctype.h>
#include <conio.h>
int main( void )
{
   int i=0;
   char ch;
   puts("Input an integer followed by a char:");
   /* read chars until non digit or EOF */
   while((ch = getche()) != EOF && isdigit(ch))
      i = 10 * i + ch - 48; /* convert ASCII into int value */
   /* if non digit char was read, push it back into input buffer */
   if (ch != EOF)
      ungetch(ch);
   printf("\n\ni = %d, next char in buffer = %c\n", i, getch());
   return 0;
}

Portability

POSIX 
Win32 
ANSI C 
ANSI C++ 
 
 
 
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