Solved

C++ syntax: class inheritance, constructor

Posted on 2013-12-28
3
491 Views
Last Modified: 2013-12-28
I have a base class A, a class B which inherits from A, and I want a constructor for class B which can take an instance of class A.

#include <string>

class A
{
public:
  A(int _i, std::string _ss);
private:
  int i;
  std::string ss;
public:
  int GetI(void) { return i; }
  void SetI(int _i) { i = _i; }
  std::string Getss(void) { return ss; }
  void Setss(std::string _ss;) { ss = _ss; }
}

class B : public A
{
public:
  B(A a, float f);   //???
private:
  float f;
public:
  void Setf(float _f) { f = _f; }
  float Getf(void);
}

B::B(A a, float f)
{
???
}

Open in new window

0
Comment
Question by:deleyd
  • 2
3 Comments
 
LVL 40

Expert Comment

by:evilrix
ID: 39743725
And your question is?
0
 
LVL 32

Accepted Solution

by:
phoffric earned 250 total points
ID: 39743952
>>   B(A a, float f);   //???

B is constructed by constructing A (i.e., B's base class) and optionally along with doing whatever construction desired for B. You can use the A's default copy constructor for B's constructor. Here is one likely possibility:

  B(A a, float ff) : A(a), f(ff) {};

In this case, a's data members will be copied into B's base class data members of A.

I changed B's constructor's 2nd arg to ff not because I had to but because, in general, I just don't happen to like using the same name for different entities.
0
 
LVL 32

Expert Comment

by:phoffric
ID: 39743957
In case you would like to read up on default copy constructors, here are some links:
   http://en.cppreference.com/w/cpp/language/copy_constructor
   http://www.cplusplus.com/articles/y8hv0pDG/
   http://en.wikipedia.org/wiki/Copy_constructor
0

Featured Post

Live: Real-Time Solutions, Start Here

Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Often, when implementing a feature, you won't know how certain events should be handled at the point where they occur and you'd rather defer to the user of your function or class. For example, a XML parser will extract a tag from the source code, wh…
This article will show you some of the more useful Standard Template Library (STL) algorithms through the use of working examples.  You will learn about how these algorithms fit into the STL architecture, how they work with STL containers, and why t…
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

813 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

9 Experts available now in Live!

Get 1:1 Help Now