Having a function return three values

This is a discussion on Having a function return three values within the C++ Programming forums, part of the General Programming Boards category; In one cpp file I have three particular variables and a loop. From within this loop I want to pass ...

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    Having a function return three values

    In one cpp file I have three particular variables and a loop. From within this loop I want to pass the three variables to a function in another cpp file. Before I do this I want to pass them to an intermediate function in another cpp file for some processing.

    If that intermediate function could return three values then I'd have no problem. I've considered calling the third function from the second but I'd rather keep all the calls from within the original loop to save any future confusion. I've thought of using pointers to variables but that seems untidy, and I can only think of using global variables otherwise.

    Is there a good way of doing this or even a creative workaround?

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    Aside from passing by reference, you could create a structure which holds all your variables and return that.

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    Jack of many languages Dino's Avatar
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    Or, since you are using C++, you could create a class, pass the instance of the class, and use getters and setters to access the variables.
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    Not sure but would a class seem overkill for three floats? Would the point be to fill the class with some of the surrounding code?

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    &TH of undefined behavior Fordy's Avatar
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    Some languages (python) offer something called a tuple which seems to be just what you want. C++ doesn't offer this as it's very type conscious, though it can be achieved using the boost library

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    pointers/references are not untidy, that is the sensible thing to do.

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    In this case, use 3 references, or 1 reference to a struct/class wrapping the 3 variables.

    In this case, some people would put an empty #define ref, and use call(ref someVar) so it appears more "tidy."
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    Quote Originally Posted by alanb View Post
    Not sure but would a class seem overkill for three floats? Would the point be to fill the class with some of the surrounding code?
    What exactly does your program do? Judging by your description in your original post, it sounds like these 3 floats are 3 variables that describe an object; in which it would be a good idea to use a class.

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    Thanks for the by reference suggestions and the info on pointers, this will help me in future.

    I think I'll try a class. The more I think of it, the more it seems appropriate for later expansion.

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    you'll still want to pass that class by an indirect type to avoid superfluous temporaries.

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    Confused Magos's Avatar
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    Quote Originally Posted by Dae View Post
    In this case, some people would put an empty #define ref, and use call(ref someVar) so it appears more "tidy."
    Sucks for someone who writes int ref = 0; though...
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    Tuples are in TR1 too, by the way.
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    Dae
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    Quote Originally Posted by Magos View Post
    Sucks for someone who writes int ref = 0; though...
    Or anyone who redefines ref, luckily it's just an example name, and compilers are smart enough to throw an error if a user should use their own code or library incorrectly.
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