Thread: overload

  1. #1


    Has anyone ever heard of overloading an '+' operator and make it do subtraction.

    Scott V.

  2. #2
    Skunkmeister Stoned_Coder's Avatar
    Join Date
    Aug 2001
    It can be done but it is probably not a good idea. The closest useful example of something similar is in the stl with reverse iterators whereby operator ++ applied to the iterator will actually move you backwards through the container.
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  3. #3
    Hmm...If I were you, I would just create two different statements, rather than try to overload '+'.
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  4. #4
    Super Moderator VirtualAce's Avatar
    Join Date
    Aug 2001
    It is a good practice to overload operators relative to their original function. If + adds in its original form then your overloaded version should be a derivative of adding not subtracting. Otherwise, your code will get very confusing very fast especially with classes. If you overload + to subtract relative to a class then:

    No overload here:

    int y=10;
    int x=20;
    int sum=x+y; //Adds

    Overloaded + relative to Vector class.

    Vector Vec1;
    Vector Vec2;
    Vector Sum=Vec1+Vec2; //Subtracts

    As you can see it is not apparent from the code which version subtracts and which one adds. This is why the + relative to Vector should add and not subtract. It gives continuity and consistency to your operators.

    Just because C++ gives us the power to abuse the operators
    does not mean that we should. Imagine if someone else were to try to read your code and you had done this.

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