C++ constructor call default constructor

Question

I have a problem calling the default constructor from other in c++. In Java was something like this:

class Book {
  static private int i;
  private String s;

  public Book() {
    i++;
  }

  public Book(String s) {
    this();
    this.s = s;
  }
}

That code isn't valid C++ ( I think you already know that ). What's the question? — Ben Voigt, Jul 05 '13 at 13:51
This is a java code i need to know how will be this code in c++ — user2553917, Jul 05 '13 at 13:53
Possible duplicate of: http://stackoverflow.com/questions/17454823/invoke-another-constructor-in-the-same-class/ — Borgleader, Jul 05 '13 at 13:53
Time to read a good book on C++. http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list — John Dibling, Jul 05 '13 at 13:54

score 6 · Answer 1 · answered Jul 05 '13 at 13:53

In C++ we have delegating constructors. There are two things to know about it:

They are available only since C++11, and not all compilers already implement them.
The correct syntax is to use the constructor's initializer list:

Book(std::string s) : Book() { ... }

score 6 · Accepted Answer · answered Jul 05 '13 at 13:55

If you have a compiler capable of delegating constructor, just call the default constructor in the initializer list:

class Book
{
public:
    Book()
    { ... }

    Book(const std::string& s)
    : Book()
    { ... }
};

Else you can make a function for common initialization and call it from all constructors:

class Book
{
public:
    Book()
    { construct(); }

    Book(const std::string& s)
    {
        construct();
        // Other stuff
    }

private:
    void construct()
    { ... }
};

Strange in c# it Works fine, but in c++ not... well i will create a function that will hold the code i need. — user2553917, Jul 05 '13 at 14:06

C++ constructor call default constructor

2 Answers2