Kindly Explain the reason behind this?

This is a discussion on Kindly Explain the reason behind this? within the C++ Programming forums, part of the General Programming Boards category; hello, When i run the below code i am getting the value of copyconscount as 2 and not 3 Please ...

  1. #1
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    Kindly Explain the reason behind this?

    hello,
    When i run the below code i am getting the value of copyconscount as 2 and not 3 Please tell me why is it happening?the copy constructor is called thrice in the program and still why is it showing only 2??


    Code:
    #include <iostream.h>
    class room
    {
      int width;
      int height;
      static int copyconscount;
      public:
    	  room()
    	  {
    		  width=12;
    		  height=8;
    	  }
    	  room(room &r)
    	  {
    		 width=r.width;
    		 height=r.height;
    		 copyconscount++;
    	  }
    	  void dispcopyconscount()
    	  {
    		  cout<<copyconscount;
    		  cout<<endl<<height;
    		  cout<<endl<<width;
    	  }
    };
    int room::copyconscount;
    int main(void)
    {
     room objroom1;
     room objroom2(objroom1);
     room objroom3=objroom1;
     room objroom4;
     objroom4=objroom3;
     objroom4.dispcopyconscount();
    
     return 0;
    }

  2. #2
    C++ Witch laserlight's Avatar
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    You only invoke the copy constructor twice, i.e.,
    Code:
     room objroom2(objroom1);
     room objroom3=objroom1;
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
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    So what's the problem laserlight??just see the below code

    Code:
    int main(void)
    {
     clrscr();
     room objroom1;
     room objroom2(objroom1);
     room objroom3=objroom1;
     room objroom4=objroom3;
     objroom4=objroom3;
     objroom2.dispcopyconscount();
     return 0;
    
    }
    i am stilling calling the constructor twice but now its printing 3??

  4. #4
    C++ Witch laserlight's Avatar
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    i am stilling calling the constructor twice but now its printing 3??
    No, you are now invoking the copy constructor three times with:
    Code:
    room objroom2(objroom1);
    room objroom3=objroom1;
    room objroom4=objroom3;
    You are also invoking the copy assignment operator with:
    Code:
    objroom4=objroom3;
    And of course the default constructor with:
    Code:
    room objroom1;
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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