function: take y/ n char input: easily modified for other char input

char input_char_switch_y_n()
{
    char char_input = ' ';
    do
    {
        cout << endl << "\t\tRepeat program?  Y (Yes) /  N (No) " ;
        cin >> char_input;
        switch(char_input)
        {
            case 'Y':
            case 'y':  // allow for both upper and lower case letters
                char_input = 'Y';
                break;

            case 'N':
            case 'n':
                char_input = 'N';
                break;


            default:   //  no legal option was entered
                cout << endl
                     << " Not a valid choice. " << endl
                     << " Choose again." << endl << endl;
        }
    } while(char_input != 'Y' && char_input != 'N' );  // loop until correct input entered
    return char_input;
} // end function