为什么_kbhit（）在C程序中只能工作一次？

Question

I just wrote this little program, that should wait for the user to type something before printing each line, but it only works for the first _kbhit(), afterwards it does not wait anymore. Why's that?

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

int main(void)
{
    printf("Canada\n");
    while ( _kbhit() == 0 );

    printf("is\n");
    while ( _kbhit() == 0 );

    printf("great!");
    while ( _kbhit() == 0 );

    return 0;
}

There's no information in the function reference that _kbhit() only works once in a program.

Answer 1

While it doesn't say it that explicitly in that documentation page, you have to consume the keystroke (with getch or getche ), otherwise _kbhit will still see it. Call _getch after the while-loop before the next one:

while(_kbhit() == 0);
_getch();
// _kbhit can now be called again

Answer 2

Kninnug's answer will work, but it raises processor ussage needlessly, because while loop must execute over and over. Much better solution is to just use

_getch();

In that case program will wait for user to press any button without wasting processor time