怎么实现这个？ [英] How to implement this?
问题描述
我正在编写这个小班级日期，代表日期
由年，月和日组成。
头文件如下：
#ifndef DATE_H
#define DATE_H
class Date {
static const int daysInMonth [] = {0,31,28,31,30,31,30,31,31，
30,31,30,31};
public：
int year;
int month;
int day;
bool isLeap;
public：
Date（int y，int m，int d）：year（y），month（m），day（d）{
isLeap = isLeapYear（）;
}
bool isLeapYear（）;
静态布尔isLeapYear（int year）;
int dayInTheYear（）;
friend int operator-（const Date& left，const Date& right） ;
friend int operator ==（const Date& left，const Date& right）;
friend int operator！=（const Date& left，const Date& right） ;
朋友int op erator>（const日期& left，const Date&右边）;
朋友int操作符<（const日期&左，const日期和右边）;
};
＃ endif // DATE_H
然而，第5行（static const int daysInMonth [] = {0,31,28，
31,30,31,30,31， 31,30,31,30,31};）不编译。
错误信息是：
Date.h：5 ：错误：这里不允许使用大括号括起初始化程序
'''''令牌之前
Date.h：5：错误：静态的类内初始化无效数据成员
非整数类型''const int []''
此行用于保存并提供
$中的天数b $ b个月。
我怎样才能实现我想要的东西？
xz写道：
然而，第5行（static const int daysInMonth [] = {0,31,28，
31,30,31,30 ，31,31,30,31,30,31};）不编译。
错误信息是：
Date.h：5：错误：此处不允许使用大括号括起初始化程序
''''令牌之前
Date.h：5：错误：静态数据成员的类内初始化无效
非整数类型''const int []''
此行用于保存并提供
个月的天数。
怎么可能我实现了我想要的东西？
你必须在你的
实现源文件（.cpp）中的类定义之外初始化daysInMonth，就像这样：
//在标题中
类日期
{
static const int daysInMonth [] ;
};
//在实现文件中（Date.cpp？）
const int Date :: daysInMonth [] = {0,31,28,31,30,31,30,31,31，
31,31,30,31};
-
Miguel Guedes
- X标志着垃圾邮件发送者的地位。如果您希望通过电子邮件与我联系，
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Miguel Guedes写道：
xz写道：
>然而，第5行（static const int daysInMonth [] = {0,31,28，
31,30,31,30,31,31,30,31,30,31 };）不编译。
错误信息是：
Date.h：5：错误：此处不允许使用大括号括起初始化程序
''{''令牌
Date.h：5：错误：静态数据成员的类内初始化无效
非整数类型''const int []''
这行是为了保存并提供
月份的天数。
我怎样才能实现我想要的？
您必须在
实现源文件（.cpp）中的类定义之外初始化daysInMonth，如下所示：
BTW，这是如此因为静态成员的定义相当于
外部变量de结果 - 只有一个。
-
Miguel Guedes
- X标志着垃圾邮件发送者的地位。如果您希望通过电子邮件与我联系，
从我的地址中删除X. -
8月26日下午3:27，Miguel Guedes< miguel.a.gue ... @ gmailX.comwrote：
Miguel Guedes写道：
xz写道：
但是，第5行（static const int daysInMonth [] = {0,31,28，
31,30,31,30,31,31,30,31,30,31};）不编译。
错误信息是：
< blockquote class =post_quotes>
Date.h：5：错误：这里不允许使用大括号括起初始化程序
''{''之前令牌
Date.h：5：错误：静态数据成员的类内初始化无效
非整数类型''const int []''
此行用于保存并提供
$ b $中的天数b个月。
我怎样才能实现我想要的？
您必须在
实现源文件（.cpp）中的类定义之外初始化daysInMonth，像这样：
感谢您的回复
BTW，这是因为静态成员的定义相当于
外部变量定义 - 只有一个。
这也适用于静态成员函数，对吗？
例如...中定义的函数static bool isLeapYear（int year）; "是
也像外部函数一样？
然而，我发现如果我有Date的实例，比如说，Date
date（...）;
我无法通过
Date.isLeapYear（2000）;
调用函数isLeapYear（int year）
相反，我可以通过
date.isLeapYear（2000）来调用它。
这对我来说很奇怪，因为isLeapYear（int）是静态的。第二个
方式调用它看起来像是theLeapYear是一个成员函数。
>
- -
Miguel Guedes
- X标志着垃圾邮件发送者的地位。如果您希望通过电子邮件与我联系，
从我的地址中删除X. -
I am coding for this little class Date, which represents the date
consisting of year, month and day.
The header file is as follows:
#ifndef DATE_H
#define DATE_H
class Date {
static const int daysInMonth[] = {0, 31, 28, 31, 30, 31, 30, 31, 31,
30, 31, 30, 31};
public:
int year;
int month;
int day;
bool isLeap;
public:
Date(int y, int m, int d):year(y), month(m), day(d) {
isLeap = isLeapYear();
}
bool isLeapYear();
static bool isLeapYear(int year);
int dayInTheYear();
friend int operator-(const Date& left, const Date& right);
friend int operator==(const Date& left, const Date& right);
friend int operator!=(const Date& left, const Date& right);
friend int operator>(const Date& left, const Date& right);
friend int operator<(const Date& left, const Date& right);
};
#endif //DATE_H
However, the 5th line (static const int daysInMonth[] = {0, 31, 28,
31, 30, 31, 30, 31, 31, 30, 31, 30, 31};) does not compile.
The error information is :
Date.h:5: error: a brace-enclosed initializer is not allowed here
before ''{'' token
Date.h:5: error: invalid in-class initialization of static data member
of non-integral type ''const int []''
This line is to save and provide the numbers of the days in the
months.
How could I implement what I want ?
xz wrote:However, the 5th line (static const int daysInMonth[] = {0, 31, 28,
31, 30, 31, 30, 31, 31, 30, 31, 30, 31};) does not compile.
The error information is :
Date.h:5: error: a brace-enclosed initializer is not allowed here
before ''{'' token
Date.h:5: error: invalid in-class initialization of static data member
of non-integral type ''const int []''
This line is to save and provide the numbers of the days in the
months.
How could I implement what I want ?
You must initialize daysInMonth outside the class definition in your
implementation source file (.cpp), like so:
// In header
class Date
{
static const int daysInMonth[];
};
// In implementation file (Date.cpp?)
const int Date::daysInMonth[]= {0, 31, 28, 31, 30, 31, 30, 31, 31,
30, 31, 30, 31};
--
Miguel Guedes
- X marks the spot for spammers. If you wish to get in touch with me by email,
remove the X from my address. -
Miguel Guedes wrote:xz wrote:>However, the 5th line (static const int daysInMonth[] = {0, 31, 28,
31, 30, 31, 30, 31, 31, 30, 31, 30, 31};) does not compile.
The error information is :
Date.h:5: error: a brace-enclosed initializer is not allowed here
before ''{'' token
Date.h:5: error: invalid in-class initialization of static data member
of non-integral type ''const int []''
This line is to save and provide the numbers of the days in the
months.
How could I implement what I want ?
You must initialize daysInMonth outside the class definition in your
implementation source file (.cpp), like so:BTW, this is so because the definition of static members is equivalent to an
external variable definition - there is only one.
--
Miguel Guedes
- X marks the spot for spammers. If you wish to get in touch with me by email,
remove the X from my address. -
On Aug 26, 3:27 pm, Miguel Guedes <miguel.a.gue...@gmailX.comwrote:Miguel Guedes wrote:xz wrote:However, the 5th line (static const int daysInMonth[] = {0, 31, 28,
31, 30, 31, 30, 31, 31, 30, 31, 30, 31};) does not compile.
The error information is :
Date.h:5: error: a brace-enclosed initializer is not allowed here
before ''{'' token
Date.h:5: error: invalid in-class initialization of static data member
of non-integral type ''const int []''
This line is to save and provide the numbers of the days in the
months.
How could I implement what I want ?
You must initialize daysInMonth outside the class definition in your
implementation source file (.cpp), like so:
Thanks for your reply
BTW, this is so because the definition of static members is equivalent to an
external variable definition - there is only one.And this also holds for the static member functions, right?
e.g. the function defined in " static bool isLeapYear(int year); " is
also like an external function?
However, I found that if I have a instance of Date, say, Date
date(...);
I cannot call the function isLeapYear(int year) by
Date.isLeapYear(2000);
But instead, I can call it by
date.isLeapYear(2000);
This looks strange for me since isLeapYear(int) is static. The second
way to call it looks like that isLeapYear is a member function.
>
--
Miguel Guedes
- X marks the spot for spammers. If you wish to get in touch with me by email,
remove the X from my address. -
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