为什么C打印两次？

Question

我确定这很简单，但有人可以告诉我为什么下面的代码会打印两次用户提示吗？提前谢谢。

#include <stdio.h>
int main(void) {
    char task = 't';
    while (task != 'q') {
        printf("What do you want to do? (quit with 'q'): ");
        scanf("%c", &task);
    }
}

输出：

What do you want to do? (quit with 'q'): a
What do you want to do? (quit with 'q'): What do you want to do? (quit with 'q'): b
What do you want to do? (quit with 'q'): What do you want to do? (quit with 'q'): c
What do you want to do? (quit with 'q'): What do you want to do? (quit with 'q'): q

它退出＆＃39; q＆＃39;喜欢它。谢谢你的帮助。