a data member that has no default contructor?

This is a discussion on a data member that has no default contructor? within the C++ Programming forums, part of the General Programming Boards category; hi Guys, i basicly want a class that has no default constructor as a data member of another class. something ...

  1. #1
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    a data member that has no default contructor?

    hi Guys,

    i basicly want a class that has no default constructor as a data member of another class. something like this:

    Code:
    class A
    {
    public:
    	A( int x );
    };
    
    class B //other class
    {
    private:
    	A objectA;
    public:
    	B( int x );
    };
    A B::objectA = A( 0 );
    my question: can it be done?
    i would appreciate any help

  2. #2
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    Code:
    class A {
      public:
        A (int x) {};
    };
    
    class B {
      public:
        B (int x) : m_A (x) {}
    
      private:
        A m_A;
    };
    
    int
    main (int argc, char *argv[])
    {
      B foo (2);
    
      return 0;
    }

  3. #3
    and the hat of sweating
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    Are you asking how to prevent people from using the default constructor?
    Simple, make the default constructor private.
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

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  4. #4
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by cpjust
    Are you asking how to prevent people from using the default constructor?
    I think symbiote is asking how to initialise a member variable of a type that has no default constructor, in which case edoceo's suggestion of using the constructor initialisation list is correct.
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  5. #5
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    Quote Originally Posted by laserlight View Post
    I think symbiote is asking how to initialise a member variable of a type that has no default constructor, in which case edoceo's suggestion of using the constructor initialisation list is correct.
    Ah yes, after re-reading it, now that makes sense.
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

    "the internet is a scary place to be thats why i dont use it much." - billet, 03/17/2010

  6. #6
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    thanks for the replies.
    i almost forgot i asked this question.
    i wanted a class that must to be initialized.
    thanks edoceo. that's exactly what i was looking for.

    Greetings

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