以下是问题：
定义一个名为Month的类，它是一个月的抽象数据类型。您的类将有一个int类型的成员变量来表示一个月（1表示1月，2表示2月，依此类推）。包括以下所有成员函数：一个构造函数，使用月份名称中的前三个字母将月份设置为三个参数，构造函数使用整数作为参数设置月份（1表示1月，2表示2月，以及所以，一个默认构造函数，一个读取月份为整数的输入函数，一个读取月份作为月份名称中前三个字母的输入函数，一个输出函数将月份作为整数输出，输出函数，输出月份作为月份名称中的前三个字母，以及一个成员函数，返回下个月作为Month类型的值。将您的班级定义嵌入测试程序中。
#include <iostream>
using namespace std;
class Month
{
public:
Month (char letter1, char letter2, char letter3);
Month (int numOfMonth);
Month ();
void inputAsNum(); // read month as integer
void inputAsCh(); // read first three chars of month
void outputAsCh() const;
void outputAsNum() const;
Month nextMonth();
private:
int month;
};
int main()
{
Month test(5);
//test.inputAsNum();
cout << "Current month is " << endl;
test.outputAsCh();
test.outputAsNum();
cout << endl;
test.nextMonth();
cout << "Next month is " <<endl;
test.outputAsCh();
test.outputAsNum();
cout << endl;
Month test2('a','p','r');
//test2.inputAsCh();
cout << "Current month is " << endl;
test2.outputAsCh();
test2.outputAsNum();
cout << endl;
test2.nextMonth();
cout << "Next month is " <<endl;
test2.outputAsCh();
test2.outputAsNum();
cout << endl;
Month test3;
test3.inputAsNum();
cout << "Current month is " << endl;
test3.outputAsCh();
test3.outputAsNum();
cout << endl;
test3.nextMonth();
cout << "Next month is " <<endl;
test3.outputAsCh();
test3.outputAsNum();
cout << endl;
Month test4;
test4.inputAsCh();
cout << "Current month is " << endl;
test4.outputAsCh();
test4.outputAsNum();
cout << endl;
test4.nextMonth();
cout << "Next month is " <<endl;
test4.outputAsCh();
test4.outputAsNum();
cout << endl;
return 0;
}
Month::Month (char letter1, char letter2, char letter3)
{
if ((letter1 == 'j')&&(letter2 == 'a')&&(letter3 == 'n'))
month= 1;
else if ((letter1 == 'f')&&(letter2 == 'e')&&(letter3 == 'b'))
month= 2;
else if ((letter1 == 'm')&&(letter2 == 'a')&&(letter3 == 'r'))
month= 3;
else if ((letter1 = 'a')&&(letter2 == 'p')&&(letter3 == 'r'))
month= 4;
else if ((letter1 == 'm')&&(letter2 == 'a')&&(letter3 == 'y'))
month= 5;
else if ((letter1 == 'j')&&(letter2 == 'u')&&(letter3 == 'n'))
month= 6;
else if ((letter1 == 'j')&&(letter2 == 'u')&&(letter3 == 'l'))
month= 7;
else if ((letter1 == 'a')&&(letter2 == 'u')&&(letter3 == 'g'))
month= 8;
else if ((letter1 == 's')&&(letter2 == 'e')&&(letter3 == 'p'))
month= 9;
else if ((letter1 == 'o')&&(letter2 == 'c')&&(letter3 == 't'))
month= 10;
else if ((letter1 == 'n')&&(letter2 == 'o')&&(letter3 == 'v'))
month= 11;
else if ((letter1 == 'd')&&(letter2 == 'e')&&(letter3 == 'c'))
month= 12;
}
Month::Month (int numOfMonth)
:month(numOfMonth)
{ }
Month::Month ()
:month(1)
{ }
void Month::inputAsNum()
{
int num;
cout << "Enter num of month => ";
cin >> num;
month = num;
}
void Month::inputAsCh()
{
char c1,c2,c3;
cout << "Enter three letters of month => ";
cin >> c1 >> c2 >> c3;
Month::Month(c1,c2,c3);
}
void Month::outputAsCh() const
{
if (month == 1)
cout << "Jan ";
else if (month == 2)
cout << "Feb ";
else if (month == 3)
cout << "Mar ";
else if (month == 4)
cout << "Apr ";
else if (month == 5)
cout << "May ";
else if (month == 6)
cout << "Jun ";
else if (month == 7)
cout << "Jul ";
else if (month == 8)
cout << "Aug ";
else if (month == 9)
cout << "Sep ";
else if (month == 10)
cout << "Oct ";
else if (month == 11)
cout << "Nov ";
else if (month == 12)
cout << "Dec ";
}
void Month::outputAsNum() const
{
cout << month;
}
Month Month::nextMonth()
{
if (month < 12)
month++;
else if (month == 12)
month = 1;
return Month(month);
}
代码运行得很好。我尝试从成员函数Month::Month (char letter1, char letter2, char letter3)调用构造函数void Month::inputAsCh()。我可以通过更改Month::inputAsCh()的定义并将构造函数的粘贴定义复制到函数中来解决问题。但是，出于好奇，可以从成员函数调用构造函数吗？如果它有问题，Month::inputAsCh()工作错误，我也会试用Month test4变量。
Output Expected Output
------------- -----------------
Current month is Current month is
Nov 11 Nov 11
Next month is Next month is
Dec 12 Dec 12
Current month is Current month is
Apr 4 Apr 4
Next month is Next month is
May 5 May 5
Enter num of month => 2 Enter num of month => 2
Current month is Current month is
Feb 2 Feb 2
Next month is Next month is
Mar 3 Mar 3
Enter three letters of month => apr Enter three letters of month => apr
Current month is Current month is
Jan 1 Apr 4
Next month is Next month is
Feb 2 May 5
答案 0 :(得分：2)
Month::Month(c1,c2,c3);
该行不会更新当前对象。它应该是一个错误，因为Month::Month在该上下文中命名构造函数，但是一些编译器（特别是clang）会将其解释为临时对象的构造（感谢用户657267进行更正）。 / p>
您可以将月份计算代码分解为单独的函数，然后从构造函数和inputAsCh函数中调用它：
void setMonth(char letter1, char letter2, char letter3)
{
if ((letter1 == 'j')&&(letter2 == 'a')&&(letter3 == 'n'))
month= 1;
else if ((letter1 == 'f')&&(letter2 == 'e')&&(letter3 == 'b'))
month= 2;
else if ((letter1 == 'm')&&(letter2 == 'a')&&(letter3 == 'r'))
month= 3;
else if ((letter1 = 'a')&&(letter2 == 'p')&&(letter3 == 'r'))
month= 4;
else if ((letter1 == 'm')&&(letter2 == 'a')&&(letter3 == 'y'))
month= 5;
else if ((letter1 == 'j')&&(letter2 == 'u')&&(letter3 == 'n'))
month= 6;
else if ((letter1 == 'j')&&(letter2 == 'u')&&(letter3 == 'l'))
month= 7;
else if ((letter1 == 'a')&&(letter2 == 'u')&&(letter3 == 'g'))
month= 8;
else if ((letter1 == 's')&&(letter2 == 'e')&&(letter3 == 'p'))
month= 9;
else if ((letter1 == 'o')&&(letter2 == 'c')&&(letter3 == 't'))
month= 10;
else if ((letter1 == 'n')&&(letter2 == 'o')&&(letter3 == 'v'))
month= 11;
else if ((letter1 == 'd')&&(letter2 == 'e')&&(letter3 == 'c'))
month= 12;
}
Month::Month (char letter1, char letter2, char letter3)
{
setMonth(letter1, letter2, letter3);
}
void Month::inputAsCh()
{
char c1,c2,c3;
cout << "Enter three letters of month => ";
cin >> c1 >> c2 >> c3;
setMonth(c1,c2,c3);
}
顺便提一下，通过从setMonth创建std::string并与之进行比较，可以大大简化您的char功能。