CODEWITHSUNDEEP
c++visual-studio-2012macroscompilation
Jebathon
Jebathon

Reputation: 4581

C++ Visual Studio "Disgusting Macro Hack" compilation issue

I am trying to re-create the vector class for my own understanding. I came across an issue recently with Visual Studio 2013 while trying to compile this code. I am getting an error for each 'vector' keyword that states:

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I do not know if this is a range error within my class definition or if this is something else.I have not played with any settings.

 #include "../../../std_lib_facilities.h"

    class vector{
        int sz;
        double* elem; //pointer to the first element (of type double)

    public:
        vector(int s) :sz(s), //constructor - allocates s doubles , :size(s) is a 'initilization list'
            elem(new double[s])
        {
            for (int i = 0; i < s; i++)
                elem[i] = 0; //initialize elements

        }

        int size() const
        {
            return sz;
        }

        //read
        double get(int n)
        {
            return elem[n];
        }

        //write
        void set(int n, double v)
        {
            elem[n] = v;
        }


        //Every class that owns a resource needs a destructor
        ~vector() //destructor
        {
            delete[] elem; // free memory
        }

    };


    int main(int argc)
    {
        vector v(5);
        for (int i = 0; i < v.size(); i++){
            v.set(i, i);
            cout << "v[" << i << "]==" << v.get(i) << '\n';
        }
        system("PAUSE");

    }

If you need any more information please don't hesitate to ask.

Upvotes: 0

Views: 800

Answers (2)

David Brown
David Brown

Reputation: 13536

I'm assuming this is the std_lib_facilities.h you have included. That file contains a macro 

// disgusting macro hack to get a range checked vector:
#define vector Vector

This causes all following occurrence of vector in your code to be replaced by Vector. So when you declare your class vector it gets changed to class Vector, and since the header you have included already declares a template type named Vector, you probably get a redefined symbol error. In addition, in main when you declare vector v(5); it gets changed to Vector v(5), and since the the original Vector class declared in std_lib_facilities.h requires a template argument, you get the error message posted in your question about a missing template argument.

To solve this you could either rename your class to something other than vector, you could #undef vector after you include std_lib_facilities.h, or you could not include that header at all and just #include <iostream> since the only part of the standard library you are using is std::cout.

Upvotes: 1

Serdalis
Serdalis

Reputation: 10489

While searching online, I found your header file... which contains the line:

// disgusting macro hack to get a range checked vector:
#define vector Vector

I don't know why you are using it, but this is the cause of your problem.

To use a vector all you need to do is #include <vector>

To add some clarification, the header file creates a vector class called Vector and then the #define makes sure that all initialisations of vector will actually refer to this Vector class.

Renaming your class will get rid of this issue for you.

As a side note, that header file is horrid, be careful when using it.

Upvotes: 1

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