fork download
copy 
  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. //secondClass needs to know the type firstClass exists to take it as an argument to the ctor
  6. class firstClass;
  7.  
  8. class secondClass
  9. {   
  10.   public:
  11.     secondClass(int val = 0): value(val){}
  12.     secondClass(const firstClass& fc); //Just declare that this function exists
  13.  
  14.     int getValue()
  15.     {
  16.         return value;
  17.     }
  18.  
  19.     int value;
  20. };
  21.  
  22. class firstClass
  23. {
  24. private:
  25.     int value;
  26.  
  27.     //Since this function is declared, this works
  28.     friend secondClass::secondClass(const firstClass& fc);
  29. public:
  30.     firstClass(int val = 0): value(val){}
  31.  
  32. };
  33.  
  34. //Finally, now that firstClass is implemented, we can implement this function
  35. secondClass::secondClass(const firstClass& fc)
  36. {
  37.     value = fc.value;
  38. }
  39.  
  40. int main()
  41. {
  42.     firstClass fc(5);
  43.     secondClass sc(fc);
  44.  
  45.     cout<<sc.value;
  46.  
  47. }
Success #stdin #stdout 0s 4544KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
5
https://ideone.com/ZvXIpw
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!