C++ Requirements

for Advanced Programming Techniques in Computer Vision

If you can solve the following problems and answer the questions you probably have the basic knowledge of C++.
Do not panic if not all of your answers are perfect, but most of them should be. If you would like to review or "activate" you C++ knowledge, you can find my suggestion for basic books here.

I strongly suggest to try out yourself and write these programs before you check the solutions!

Problem #1

Write a small C++ program that prints "Hello World" on the standard output.
Solution (select it to appear):

#include <iostream>
int main()
{
 std::cout << "Hello World" << std::endl;
 return 0;
}

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Problem #2

Create a header file Person.h Write a small class called Person with two properties: name, age.
The class should have a minimal interface that works with the following main program:

#include <iostream>
#include "Person.h"

using namespace std;

int main(){
 Person p1("Paul", 20);
 const Person p2("Peter", 22);
 Person p3("James", 24);
 cout << p1 << p2 << p3 << endl;
 p1 = p2;
 p1.setName("John");
 cout << p1.getName() << " and " << p2.getName()
 << " are both " << p1.getAge() << " years old.\n";
 return 0;
}

Note: in realty you should separate Person's implmentation to Person.cpp, however, for simplicity the solution defines all function to be inline.
Solution (select it to appear):

#ifndef PERSON_H
#define PERSON_H

#include<ostream>
#include<string>

// should never use "using namespace ..." in a global namespace in a header file!

class Person {
 public:

 Person(std::string s, int a): name(s), age(a) {}

 // make get... methods const, so
 // - it can be called on const objects
 // - to indicate that get... methods do not change the object state
 std::string getName() const { return name; }
 void setName(std::string s) { name = s; }

 int getAge() const { return age; }
 void setAge(int a) { age = a; }

 private: // in general we do not give access member variables
 std::string name;
 int age;
};

// Note: the following operator does not have to be friend of Person, because
// it can be efficiently implemented by the public interface of Person.
inline std::ostream& operator<<(std::ostream& out, const Person& p){
 out << "Name: " << p.getName()
 << "\nAge: " << p.getAge() << "\n";
 return out;
}
#endif // PERSON_H

// For an additional challenge, you can try to use C-like strings (char*)
// instead of std::string. Notice that the implementation will be more
// complicated, since Person has a pointer member, and therefore each object
// has to take care of its memory allocation.

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Questions

1. What is inheritence?
2. What are virtual methods?
3. What is a constructor?
   
4. What is an abstract class?
5. When does a programmer need a virtual destructor?
6. What is a recursive function?
7. What is the difference between the * and the &?