c++ How do I get variables from a class and put it into another class, and put it into a constructor? -

i have 2 h , cpp files. wanna know how call variables abe.h file or abe class bob.h or bob class. please help.

abe.h

#include <iostream> using namespace std; #ifndef abe #define abe  class abe {     private:     int num;      public:         abe();         abe(int);         void shownumber();  }; #endif // abe 

abe.cpp

#include "abe.h" #include <iostream>  using namespace std;  abe::abe() {     num=45; }  abe::abe(int n) {     num=n; }  void abe::shownumber() {     cout<<num; } 

bob.h

#include "abe.h" #include <iostream>  using namespace std; #ifndef bob #define bob  class bob { private:     abe a;  public:     bob(abe);     void shownum(); };  #endif // bob 

bob.cpp

#include "abe.h" #include "bob.h" #include <iostream>  using namespace std;  bob::bob(abe a1) {     a=a1;   //^not sure a=a1 doing if explain in simple terms or in deatil help. }  void bob::shownum() {     //how display here?? } 

so how "num" abe class , use in bob class? please help. thank you!

a=a1assigns abe passed bob's constructor bob's a member. idea use more descriptive variable names , there optimizations gained using initializer list. example:

bob::bob(abe a1):a(a1) { } 

now bob has abe, can... nothing number abe. abe has allow bob number. redefine abe in 1 of 2 ways:

class abe {     private:     int num;      public:         abe();         abe(int);         void shownumber();         int getnumber()         {             return num;         } }; 

now bob can

int number = a.getnumber(); 

or (and second because less preferred option because tightly couples bob , abe.

class abe {     friend class bob;     private:     int num;      public:         abe();         abe(int);         void shownumber(); }; 

bob has total access internals of abe , can mess poor guy if wants to. not nice. anyway, bob can now

int number = a.num; 

bob can read num, change num, set hopelessly bad values , jerk abe. thing bob friend. other downside bob needs know how abe works on inside , if abe's code changed, bob have change well.