C++ Input Validation Class

I'm learning to program. All of my programs for my assignments are console applications. Sometimes things get fancy with fstream and text files, but I'm doing beginner work.

A lot of my programs ask for user input. Since they're console applications, it's console input. I always have to write a while loop that checks for invalid input and loops until the input is valid. What a pain!

So I want to write an input class. The class will have virtual functions and use templates. I want to have the function work like this:

InputVal inv; //declaration of instance of InputVal class object "inv"

inv(variable); //variable can be a double or int. later i will add char support to the class. takes variable by reference and a virtual function is chosen based on the variable's type

The virtual function would be so I can have the class appropriately choose its function based on the type of variable passed as a parameter. A template would be so I don't have to write the same function twice for short, double, int, long int, etc. I wonder if I need to use a virtual function AND a template or if I can just use a template...

:)

#include <iostream>
#include <typeinfo> //for error message in inVal(T)
using namespace std;

/*==========================
sum is a template function that can accept generic types and return
the same type.
===========================*/
template <class T>
T sum(T a, T b) { return a+b; }

/*==========================
inVal accepts generic types by reference and performs input
validation. I often write a function like this in my programs,
so I thought, why not make a template out of it? It works for
doubles and ints.
It doesn't really work for a char. It will run,
but it won't work as intended since anything from keyboard counts
as a char. You could enter "DDDDDDDDDDD" and the program would
just write the first D to the char and leave the other D's in the
input stream.
===========================*/
template <class T>
void inVal(T &input)
{
    cin >> input;
    while(!input)
    {
        cout << "Valid input requires " << typeid(input).name() << endl;
        cin.clear();
        cin.ignore(10,'\n');
        cin >> input;
    }
    return;
}
/*==========================
Main is just for testing the functions I wrote.
Nothing special.
===========================*/
int main()
{
    int a=1,b=3;
    double a1 = 5, b1 = 6;
    char ch;
    cout << sum(a,b);
    cout << endl << sum(a1,b1);
    inVal(a);
    inVal(a1);
    inVal(ch);
    cout << endl << a;
    return 0;
}