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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class Base
  5. {
  6. public:
  7.     virtual void show_data() {
  8.         std::cout<<__PRETTY_FUNCTION__<<std::endl;
  9.     }
  10.     virtual ~Base(){}
  11. };
  12.  
  13. class Derived: public Base
  14. {
  15. public:
  16.     virtual void show_data() override {
  17.         std::cout<<__PRETTY_FUNCTION__<<std::endl;
  18.         std::cout<<"Just derived"<<std::endl;
  19.         std::cout<<"Such useful"<<std::endl;
  20.     }
  21.  
  22. };
  23.  
  24. class Special: public Base
  25. {
  26.     public:
  27.         Special(int num, const std::string &data): secret_num(num), secret_data(data)
  28.         {}
  29.  
  30.         virtual void show_data() override {
  31.             std::cout<<__PRETTY_FUNCTION__<<std::endl;
  32.             std::cout<<"Num: "<<secret_num<<std::endl;
  33.             std::cout<<"Data: "<<secret_data<<std::endl;
  34.         }
  35.  
  36.         void set_params(int num, const std::string &data){
  37.             secret_num = num;
  38.             secret_data = data;
  39.         }
  40.     private:
  41.         int secret_num;
  42.         std::string secret_data;
  43. };
  44.  
  45.  
  46. int main()
  47. {
  48.     std::vector<Base *> objects{
  49.             new Base(),
  50.             new Special(1111, "mheh"),
  51.             new Derived()
  52.     };
  53.  
  54.     for (const auto &it: objects)
  55.     {
  56.         Special *special = dynamic_cast<Special *>(it);
  57.         if (special != nullptr)
  58.         {
  59.             special->show_data();
  60.             special->set_params(0, "new data");
  61.             special->show_data();
  62.         }
  63.         else
  64.         {
  65.             it->show_data();
  66.         }
  67.         std::cout<<"========="<<std::endl;
  68.     }
  69.  
  70.     for (auto &it: objects){
  71.         delete it;
  72.     }
  73. }
Success #stdin #stdout 0s 3472KB
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stdin
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Standard input is empty
stdout
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virtual void Base::show_data()
=========
virtual void Special::show_data()
Num: 1111
Data: mheh
virtual void Special::show_data()
Num: 0
Data: new data
=========
virtual void Derived::show_data()
Just derived
Such useful
=========
https://ideone.com/Q3qnZv
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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