c++ - 在 C++ 中用两个 char 变量评估 bool 值

Question

抱歉，这里有点初学者:

我正在研究一个练习程序，根据一天中的小时数和一周中的几天来确定长途电话的费用……我已经进入了 do-while 循环并尝试使用嵌套分支机构将工作日与周末分开。

但是，当我编译和运行时，无论我是否放入对应于我试图计算的 bool 值的字符，if 和 else if 嵌套语句都会被跳过。我正在努力了解我在这里缺少的东西。说明中明确指出星期几应存储在两个字符变量中:Mo Tu We Th Fr Sa Su。

do
{
    //have user input day of week of call
    printf("\nOn what day was the call made? (Mo, Tu, We, Th, Fr, Sa, or Su) ");
    scanf("%c%c", &day1, &day2);

    //branch for weekday vs weekend vs invalid input
    if (((day1 == 'M') && (day2 == 'o')) || ((day1 == 'T') && (day2 == 'u')) || ((day1 == 'W') && (day2 == 'e')) || ((day1 == 'T') && (day2 == 'h')) || ((day1 == 'F') && (day2 == 'r')))
    {
        //determine if phone call was made at hi or low rate times
        printf("At what time was your call made? (HH MM - with 08 00 representing 8:00 AM and 18 30 representing 6:30 PM) ");
        scanf("%f %f", &call_time_hour, &call_time_minute);
        call_time_hour = call_time_hour + (call_time_minute / 60);

        printf("%f", call_time_hour);
    }
    else if (((day1 == 'S') && (day2 == 'a')) || ((day1 == 'S') && (day2 == 'u')))
    {
        printf("What was the duration of your call? ");
        scanf("%d", &call_duration);

        //calculate total cost of call
        cost_of_call = call_duration * 0.15;

        printf("%s %.2lf", "The cost of this call was $", cost_of_call);
    }
    calls_made--;
    printf("%d", calls_made);
}while (calls_made > 0);

因此，例如，当我编译并运行程序并输入“Sa”作为调用日期时，它会直接移动到“calls_made--”步骤。

Answer 1

问题是因为之前的scanf。调试并查看真正扫描的字符。我确定 day1 会是 '\n'。

在这种情况下，在扫描星期几之前清除输入流:

while (getchar() != '\n');