對象沒有聲明，無法在類中顯示

Question

我做了一個簡單的程序，試圖瞭解構成。我查了一遍這個程序，但是我不知道爲什麼我的「birthobj」沒有被聲明，我的「printDate（）」沒有被聲明。如果您能提供一些見解，我將非常感激。

• 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(); 
      } 
  

編譯消息：

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

Answer 1

你定義的變量birthObj但使用birthobj。請注意，在C++中，標識符是區分大小寫的。只需將您的代碼更改爲

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

它會工作。當然，printInfo與printinfo相同。