Основное меню на C ++

У меня вопрос, который должен быть простым, но я не могу найти ответ нигде.

У меня есть программа с управляемым меню C++, которая отлично работает, когда параметры меню являются номерами, но я не могу понять, как изменить числа на буквы.

Например:

работает отлично, когда выбор 1, 2 или 3, но не A, B, C.

Не уверен, как я должен объявить вариант... это символ? заранее спасибо

#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
    //Variables needed for the problem
    int numbServCharge; //number of service charges
    char choice; //menu choice
    double transAmt, balence, totalServCharge; //transaction amount, current balence, total service charges

    //Constant service change
    const double servCharge = 0.25; //constant $0.25 for service charges

    numbServCharge = 0; //Start the counter for number of service charges at zero
    cout << "Checkbook Balencing Program\n\n";
    cout << "Enter the beginning balence:  "; 
    cin >> balence; //get the initial balence
    cout << endl;

    do
    {
        //Highlight menu options
        cout << "\nCommands\n";
        cout << "C - process a check\n";
        cout << "D - process a deposit\n";
        cout << "E - end the program\n\n";

        //Get user choice from menu
        cout << "Enter transaction type:  ";
        cin >> choice;
        cout << endl;

        //Create an error message for invalid choice and get a second choice
        while((choice != 'C') && (choice != 'D') && (choice != 'E')
        {
            cout << "Invalid selection.  Please choose C, D or E: ";
            cin >> choice;
        }

        //Set up for option #1 -- using a check
        if(choice=='C')
        {
            cout << "Enter transaction amount:  ";
            cin >> transAmt; //Get the amount of the check
            cout << "\nProcessing check for $" << fixed << setprecision(2) << transAmt;
            transAmt = transAmt + servCharge; //Add the service charge onto the transaction
            numbServCharge++; //Add one to the number of service charges there have been
            balence = balence - transAmt; //Update account balence
            cout << "\nBalence:  $" << fixed << setprecision(2) << balence;
            cout << "\nService charge:  $0.25 for a check\n";
            totalServCharge = servCharge * numbServCharge; //Update total cost of service charges
            cout << "Total service charges:  $" << fixed << setprecision(2) << totalServCharge << endl; //Tell user total service charges so far
        }

        //Set up for option #2 -- deposits
        if(choice=='D')
        {
            cout << "Enter transaction amout:  ";
            cin >> transAmt; //Get the amount of the deposit
            cout << "\nProcessing Deposit for $" << fixed << setprecision(2) << transAmt << endl;
            transAmt = transAmt - servCharge; //Add the service charge onto the deposit
            numbServCharge++; //Add one to the number of service charges there have been
            balence = balence + transAmt; //Update account balence
            cout << "Balence:  $" << fixed << setprecision(2) << balence << endl;
            totalServCharge = servCharge * numbServCharge; //Update total cost of service charges
            cout << "Total service charges:  $" << fixed << setprecision(2) << totalServCharge << endl; //Tell user total service charges so far
    }

    }while(choice != 'E'); //Close program if option 3 is selected

    //Display final balence
    cout << "Processing end of the month";
    cout << "\nFinal balence :  $  " << fixed << setprecision(2) << balence << endl << endl;

    system("pause"); //Pause screen so it doesn't close right away
    return 0;
}