Question

我知道我可以使用日期格式化程序，但我正在尝试学习。

我正在尝试以Scanner格式mm/dd/yyyy开始约会。当我接受本月的输入时，我遇到了麻烦。例如，如果我想要1月份，请按01，monthInt将其转换为1而不是01。

我也遇到了麻烦。当我输入有效日期时，它一直说无效的一天。我的if声明搞砸了吗？如果您需要更多解释，请询问。谢谢你的时间！

我的代码：

    System.out.println("Enter a date in the format mm/dd/yyyy");
    String mm;
    String dd;
    String yyyy;
    String January = null;
    String February = null;
    String March = null;
    String April = null;
    String May = null;
    String June = null;
    String July = null;
    String August = null;
    String September = null;
    String October = null;
    String November = null;
    String December = null;
    String month = null;
    String date = null;

    Scanner keyboard = new Scanner(System.in);

    date = keyboard.next();
    if (date.length() != 10) {
        System.out.println("Format of date is wrong");
    }
    if (date.charAt(2) != '/') {
        System.out.println("Must have / after mm");
    }
    if (date.charAt(5) != '/') {
        System.out.println("Must have / after dd");
    }

    else if (date.length() == 10 && date.charAt(2) != '/' && date.charAt(5) != '/') {
        System.out.println(date + " date is valid");
    }

    mm = date.substring(0, 1);
    int monthInt = Integer.parseInt(mm);        

    if (monthInt == 1) {
        month = January;
    } else if (monthInt == 2) {
        month = February;
    } else if (monthInt == 3) {
        month = March;
    } else if (monthInt == 4) {
        month = April;
    } else if (monthInt == 5) {
        month = May;
    } else if (monthInt == 6) {
        month = June;
    } else if (monthInt == 7) {
        month = July;
    } else if (monthInt == 8) {
        month = August;
    } else if (monthInt == 9) {
        month = September;
    } else if (monthInt == 10) {
        month = October;
    } else if (monthInt == 11) {
        month = November;
    } else if (monthInt == 12) {
        month = December;
    } else {
        System.out.println("Invalid Month");
    }

    if (monthInt < 0 || monthInt > 12) {
        System.out.println("Invalid month");
    }

    dd = date.substring(3, 4);
    int dayInt = Integer.parseInt(dd);

    if (monthInt == 1 || monthInt == 3 || monthInt == 5 || monthInt == 7 || monthInt == 8 || monthInt == 10
            || monthInt == 12 && dayInt < 0 && dayInt > 31) {
        System.out.println("Invalid day");
    }

    if (monthInt == 4 || monthInt == 6 || monthInt == 9 || monthInt == 11 
             && dayInt < 0 && dayInt > 30) {
        System.out.println("Invalid day");

    }
    if (monthInt == 2 && dayInt < 0 && dayInt > 28){
        System.out.println("Invalid day");
    }

Answer 1

您在无效日检查中的if语句不正确。它应该是这样的：

if ((monthInt == 1 || monthInt == 3 || monthInt == 5 || monthInt == 7 || monthInt == 8 || monthInt == 10 || monthInt == 12) && (dayInt <= 0 || dayInt > 31)) {
    System.out.println("Invalid day");
}

if ((monthInt == 4 || monthInt == 6 || monthInt == 9 || monthInt == 11) && (dayInt <= 0 || dayInt > 30)) {
    System.out.println("Invalid day");
}

if (monthInt == 2 && (dayInt <= 0 || dayInt > 28)) {
    System.out.println("Invalid day");
}

请注意，dayInt < 0语句已更改为dayInt <=0，因为0的日期int也无效。

这里的关键是，如果它是给定月份之一，您希望它是无效日，并且它超出该月的日期范围。因此，您使用if(month1 OR month2 etc) AND (outsiderange1 OR outsiderange2)形式的复合词。

Answer 2

看起来问题就在这里：

mm = date.substring(0, 2);

它取日期字符串中的第一个字符，因此如果您输入'01'表示1月，它将为'0'，因此monthInt将为0，您将收到“无效月份”错误。如果您想获得两个字符，则需要dd = date.substring(3, 5);

日期存在同样的问题，您需要df5.set_index(['Date Time'], inplace=True)

从扫描仪获取输入并生成有效日期

2 个答案: