Example of polymorphism working with data structure in C++ based on php example

Question

I am learning polymorphism and I am familiar with php.

I came across this excellent example from https://stackoverflow.com/a/749738/80353. reproduced below.

How

Answer 1

As someone not familiar with C++, create a index.cpp file and fill it up with the following

#include 
#include 
#include 

using namespace std;

class Animal {
  public:
    std::string name;
    Animal (const std::string& givenName) : name(givenName) {}
    virtual string speak () = 0;
    virtual ~Animal() {}

  };

class Dog: public Animal {
  public:
    Dog (const std::string& givenName) : Animal (givenName) {

    }
    string speak ()
      { return "Woof, woof!"; }
  };

class Cat: public Animal {
  public:
    Cat (const std::string& givenName) : Animal (givenName) {
    }
    string speak ()
      { return "Meow..."; }
  };

int main() {
    std::vector> animals;
    animals.push_back( std::unique_ptr(new Dog("Skip"))  );
    animals.push_back( std::unique_ptr(new Cat("Snowball"))  );

    for( int i = 0; i< animals.size(); ++i ) {
        cout << animals[i]->name << " says: " << animals[i]->speak() << endl;
    }

}

afterwards, compile the index.cpp file with the following command

c++ index.cpp -std=c++11 -stdlib=libc++

you need that because of the use of smart pointers unique_ptr in the code.

finally you can execute the compiled executable output file which should be a.out

./a.out