C语言解答6位密码输入检测 从键盘输入6位仅由数字0~9组成的密码。用户每输入一个密码并按回车键后，程序给出判断：如果是数字，则原样输出该数字，并提示用户目前已经输入了几位密码，同时继续输入下一位密码；否则，程序提示"error"，并让用户继续输入下一位密码。直到用户输入的密码全部是数字为止。 以下为程序的运行结果示例： Input your password: 1↙ 1, you have enter 1-bits number 6↙ 6, you have enter 2-bits number a↙ error d↙ error 4↙ 4, you have enter 3-bits number 6↙ 6, you have enter 4-bits number 8↙ 8, you have enter 5-bits number 2↙ 2, you have enter 6-bits number 输入格式:"%c" 输入提示信息："Input your password:\n" 如果输入的是数字，输出格式为："%c, you have enter %d-bits number\n" 如果输入的不是数字，输出提示信息："error\n"

下面是 C 语言代码实现：

#include <stdio.h>

int main() {
    printf("Input your password:\n");
    char ch;
    int count = 0;
    while (count < 6) {
        scanf("%c", &ch);
        if (ch >= '0' && ch <= '9') {
            count++;
            printf("%c, you have enter %d-bits number\n", ch, count);
        }
        else {
            printf("error\n");
        }
        // 清空输入缓冲区
        while (getchar() != '\n');
    }
    return 0;
}

注意在读取字符后需要清空输入缓冲区，否则会导致多次循环只读取一次字符。

运行结果示例：

Input your password:
1
1, you have enter 1-bits number
6
6, you have enter 2-bits number
a
error
d
error
4
4, you have enter 3-bits number
6
6, you have enter 4-bits number
8
8, you have enter 5-bits number
2
2, you have enter 6-bits number