Incrementing a hex value for a function parameter in a loop instead of hardcoding it?

I have a constructor that takes 9 arguments, instead of harcoding each value in an array equal to each argument I was hoping I could run through a loop and set each value of the array column/row equal to the paramater name plus a counter. I named the arguments a, b, c, d, e, f, g, h, and i to try to achieve this.

Code:

---

Matrix::Matrix(float a, float b, float c, float d, float e, float f, float g, float h, float i)
{
    int counter = 0;

    for(int i = 0; i < MAX_SIZE; i++)
        for(int j = 0; j < MAX_SIZE; j++)
            mVals[i][j] = 0x61 + counter++;

    //Don't want to hardcore 9 of these
    //mVals[0][0] = a;
    //mVals[0][1] = b;
}

---

This is what I was hoping to do, but instead its giving me the decimal value of 0x61 which is 97 + 1, +2, +3...etc.

I've tried a char() cast and I can't get anything to work. MAX_SIZE is 3, using this for a 3x3 matrix. Is this not possible since its a variable name?

Your idea would work in a scripting language, but a C++ (or C) program does not know the variable names after it is compiled. Why don't you just pass in an array?

EDIT: Actually, another idea is to use a variable argument list. See the cstdarg.h header.

EDIT2: Now that I think about it, using a variable argument list is not a very good idea as it forgoes any type checking.

Since there's only 9 values, you may as well just bite the bullet and assign them all individually.

O_o

This is C++ so I could show you a hundred different ways to emulate the look, but you'd still be doing a lot of work.

So yeah, this is one of those times when just doing the work for what you need done is for the best.

Soma

If you are programming under C++11, you can take advantage of initializer lists:

Code:

---

class Matrix
{
public:

    Matrix(std::initializer_list<float> list) noexcept
    {
        auto it = list.begin();
        for (std::size_t row = 0; row < 3; ++row)
        {
            for (std::size_t column = 0; column < 3; ++column)
            {
                if (it != list.end())
                {
                    mElements[row][column] = *it;
                    ++it;
                }
                else
                {
                    mElements[row][column] = 0;
                }
            }
        }
    }

private:

    float mElements[3][3];
};

int main()
{
    Matrix matrix{100, 200, 300, 400, 500, 600, 700};
    ...
    return 0;
}

---

This also enables you to use a variable-length argument list, which fills the unspecified elements with zeros (you can make the initializer_lists nest).
With this approach you could even make your Matrix a template and get rid of the hardcoded dimensions.

The downside is that in the case of matrix math, the initializer_list solution may turn out not to be performance-wise.