Overloaded << operator

This is a discussion on Overloaded << operator within the C++ Programming forums, part of the General Programming Boards category; Quick question. If I have a method to overload the << operator: Header: Code: ostream& operator <<(ostream &os, const Set ...

  1. #1
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    Overloaded << operator

    Quick question. If I have a method to overload the << operator:
    Header:
    Code:
    ostream& operator <<(ostream &os, const Set &s);
    In the cpp:
    Code:
    ostream& operator <<(ostream &os, const Set &s)
    {
           //print to a file
    }
    Is this the correct way to do this? I have checked around and it says it's the right way to do it but I am still getting errors.
    Last edited by DivineSlayer936; 04-07-2007 at 11:38 AM.

  2. #2
    ZuK
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    Yes it is the correct way. If you'd tell what errors you get, we might even be able to tell you why.
    Kurt

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    I get "In file included from Set.cpp"
    "expected constructor, destructor, or type conversion before '&' token"
    "expected `,' or `;' before '&' token"

    What do I have to include?

  4. #4
    ZuK
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    could be <iostream> or the header that declares Set.
    Kurt

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    The program works fine just before I included the 2 code snippets from above. I had it printing with cout and I just wanted to get the overloading code right before I actually used it in my driver.

  6. #6
    ZuK
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    I still think it should be
    Code:
    #include <iostream>
    using std::ostream;
    in Set.h
    Kurt

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    Thank you so much! That works.

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    Hate to bother you again, but is there any easy explanation for why it gives the error "undefined reference to 'Set::displaySet()'" when i declare that method as a const. It works when it isn't const.

  9. #9
    ZuK
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    I get this error when I forget to add the const in the implementation.
    Kurt

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    Hmm.

    Code:
    void displaySet() const;
    Code:
    void Set::displaySet() const
    {
         cout << "{";
         for(int i=1;i<=myList.getLength();i++)
         {
               cout<<getValue(i);
               if(i!=myList.getLength())
                    cout<<",";
         }
         cout << "}";
    }
    I changed both to const. I don't have to do anything differently when I use it throughout my cpp file do I?

  11. #11
    ZuK
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    Don't think so. What's the problem ?
    Kurt

  12. #12
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    I changed displaySet to const in both the .h and .cpp and now it gives me the error "undefined reference to 'Set::displaySet()'".

  13. #13
    ZuK
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    Don't understand why. Have you rebuilt the whole project.
    Kurt

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    You really are my hero. It worked.

  15. #15
    ZuK
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    Happens quite often. Most of the IDE's are not smart enough to check headers for dependancies.
    Kurt

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