Passing arguments to the class constructor from a different constructor?

Question

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c++ call constructor from constructor

I have two constructors for the same class and I want one of the constructors to send data to the second constructor.

I know how to do it in C# but I'm new to C++ and I don't know if this is possible like so:

class a 
{

public:
a (int x);
a (int x, int b, char g);

};

a :: a(int x) : this(x, 6, 'h')
{

}

Look at the second answer in the question I linked to if you're on C++11 — Brendan Long, Sep 18 '12 at 20:53

score 3 · Answer 1 · answered Sep 18 '12 at 20:53

3

New C++11 standard supports this feature (called delegating constructors). Syntax is like:

a::a(int x) : a(x, 6, 'h') {}

If your compiler doesn't support new standard, you will need to extract common behavior into another initialization method and call that method in the constructor body.

answered Sep 18 '12 at 20:53

Zdeslav Vojkovic

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Thx, since i'm currently not using c++11 do i have no way of doing this ?? – David Limkys Sep 18 '12 at 20:55
I have edited the answer: unfortunately not. – Zdeslav Vojkovic Sep 18 '12 at 20:56
@DavidLimkys What is stopping you from using C++11 features? Is it because your compiler does not support it? – Mihai Todor Sep 18 '12 at 20:57
Ok thx for the quick answer :D @Mihai Todor Yes i am currently using mvs 2010. – David Limkys Sep 18 '12 at 21:00

score 0 · Answer 2 · answered Sep 18 '12 at 20:58

It's possible in C++11, but not in earlier versions.

Generally, you can try putting common stuff into a (non-virtual) member function, and call that from your constructors. While this won't allow you to init everything (only stuff that you do in the constructor bodies, not initialization in the preambles), it might still be "better than nothing".

Passing arguments to the class constructor from a different constructor?

2 Answers2