User-specified datatypes

[INeedAHero]

I have a template Array class that should create objects of ints, chars, and doubles.

How could I write my main.cpp file so that the user can define the datatype of the array?

For example, I cout to the user: "What type of array do you want?" And then, based on his response (which will either be char, int or double), I instantiate an object of that type.

It seems simple enough, but my code won't compile when I do it!
Here's what my main looks like:

#include <iostream>
using namespace std;

#include "Array.h"

template<typename T> T Array<T>:: dvalue = 'X';

main()
{
        //The chief purpose of this file is to stress and test the .h file

        int size = 0;
        string yes_no;
        string cyi;
        int bad_input_ctr = 0;

        do
        {
                if(bad_input >= 1)
                        cout << "Please type either the word 'char' for char, 'int' for int, or 'double' for double\n";
                else
                        cout << "Do you want the array to be a char, int, or double? (char/int/double)?\n";
                cin >> cyi;
                bad_input_ctr++;
        } while(cyi != "char" && cyi != "int" && cyi != "double");

        if(cyi == "char")
        {
                Array<char> arr1(size);
                Array<char> arr2;
        }
        else
                if(cyi == "int")
                {
                        Array<int> arr1(size);
                        Array<int> arr2;
                }
                else
                {
                        Array<double> arr1(size);
                        Array<double> arr2;
                }

        cout << "Enter the values of the array\n";

        cin >> arr1;
}

All the other functions in my .h work with each datatype. This is the only problem.

[INeedAHero]

I made some edits to the original post in case it wasn't clear what I was asking.

Any ideas?

[Peter87]

There is no variable in scope with the name arr1 at line 46. The variables that you create on line 29-30 will go out of scope on line 31. Same problem with with the variables on lines 35-36 and 40-41.

Array<int>, Array<double> and Array<char> are three completely different types. You can't have a variable have different types.

[INeedAHero]

Then I'm stuck.

If I can't define Array<int> , Array<double> , and Array<char> separately, then how could I ever possibly instantiate on object of a type specified by the user? I don't know what kind of data type the user will want until run time.....

[Peter87]

Well, you might be able to solve it using inheritance and virtual functions. This is the usual way to solve the problem of having the type be decided at runtime.

[ResidentBiscuit]

Templates have to know the type at compile time. This isn't Java generics (which are a mess anyway). The compiler will compile a copy of your template for each type that will be using it.