Question

我制作了一个简单的程序，试图理解构图。我多次查看该程序，但我不明白为什么我的＆＃34; birthobj＆＃34;没有被宣布和我的＆＃34; printDate（）＆＃34;没有被宣布。如果你们中的任何人能够提供一些见解，我将非常感激。

Composition.cpp

     #include <iostream>
     #include "Birthday.h"
     #include "People.h"
     using namespace std;

    int main()
    {
        Birthday birthObj(11,21,1996);
        People brandanBalasingham("Brandan", birthobj);
        brandanBalasingham.printinfo();
    }

birthday.h

   #ifndef BIRTHDAY_H
   #define BIRTHDAY_H


   class Birthday
    {
        public:
            Birthday(int m, int d, int y);
            void printDate();
     private:
            int month;
            int day;
            int year;
    };

    #endif // BIRTHDAY_H

birthday.cpp

    #include "Birthday.h"
    #include <iostream>
    using namespace std;

    Birthday::Birthday(int m, int d, int y)
    {
           month = m;
           day = d;
           year = y;
    }

    void Birthday::printDate()
    {
         cout << month << "/" << day << "/" << year << endl;     
    }

people.h

   #ifndef PEOPLE_H
   #define PEOPLE_H
   #include <string>
   #include "Birthday.h"
   using namespace std;

   class People
   {
       public:
           People(string x, Birthday bo);
           void printInfo(); 
     protected:
     private:
            string name;
            Birthday dateOfBirth;
   };

    #endif // PEOPLE_H

people.cpp

    #include "People.h"
    #include "Birthday.h"
    #include <iostream>
    using namespace std; 

    People::People(string x, Birthday bo)
    : name(x), dateOfBirth(bo) // name = x, dateOfBirth = bo
    {
    }

    void People::printInfo()
    {
         cout << name << " was born on ";
         dateOfBirth.printDate();
    }

编译器消息：

'birthobj' undeclared (first use of this function)
'class People' has no member named 'printInfo'

Answer 1

您定义了变量birthObj，但使用了birthobj。请注意，在C ++中，标识符区分大小写。只需将代码更改为

即可

People brandanBalasingham("Brandan", birthObj);
//                                        ^

它会起作用。当然，printInfo与printinfo相同。

对象没有声明，无法在课堂上显示

1 个答案: