C++ :: How To Create Type Validation Function

So I am writing an assignment to Detect prime numbers and it works by Asking for how many values you are going to enter, and then saying "Enter value 1: "

Then you would input and it would calculate via for loop, and that part is working. However to make my program more foolproof, I devised a way for the user to be unable to "Break" the program by inputting characters or float values. Here is the code for that:

while(!(cin >> num)){ //num is some type (char, float, int etc.)
cout << "That is not at valid input, please try again" << endl; //"Error Message"
cin.clear();
cin.ignore(10000, '
'); //Clear and reset cin
cout << "Enter value " << n << ": "; //Re-Prompt User for input
//n is whatever value the for loop is on
}

and this code works fine, I was just curious about how i would turn it into a function. Preferably wiht the name: ValidateInput(Param1, Param2);

The Parameters of the function preferably would be the variable youre inputting and the message you want to prompt. So somehow i wish to have it so for the above example it would look like:

ValidateInput(num, "Enter Value " << n << ": ");

But I don't know exactly how to label either parameter part because I want it to work for chars, ints, floats etc. And I don't know what I want it to return if anything either.