函数名: ungetch

功 能: 把一个字符退回到键盘缓冲区中

用 法: int ungetch(int c);

程序例:

#include <stdio.h>

#include <conio.h>

#include <ctype.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("\\i = %d, next char in buffer = %c\", i, getch());

return 0;

}