int main()
{
    int continue_session = 1 ;
    do
    {
        // your entire code goes here
        printf ("do you want to continue (0 if not) ? ") ;
        scanf ("%d", &continue_session) ;
    }
    while ( continue_session != 0 ) ;
    return 0;
}

//Program adds, subtracts, multiplies, or divides any two numbers that the user enters.

#include <iostream>

using std::cout;
using std::cin;
using std::endl;

int main()
{
    char operation = ' ';
    int num1 = 0;
    int num2 = 0;
    int answer = 0;
    
    cout <<"Enter A (add) or S (subtract) or M (multiply) or D (divide): ";
    cin >> operation;
    operation = toupper(operation);

    if (operation != 'A' && operation != 'S' && operation != 'S' && operation != 'M' && operation != 'D')
//Changed this to && instead of ||
    {
        cout <<"Error: Wrong letter entered" << endl;
        return 0;
    }

    cout <<"Enter first number: ";
    cin >> num1;
    cout <<"Enter second number: ";
    cin >> num2;
    
    if (operation == 'A' || 'a')
    {
        answer = num1 + num2;
        cout <<"Sum: " << answer << endl;;
    
    }//end if

    if (operation == 'S' || 's') 
    {
            if (num1 > num2)
            {
                answer = num1 - num2;
            }//end if
            else 
                answer = num2 - num1;

        cout <<"Difference: " << answer << endl;
    }//end if
    
    
    if (operation == 'M' || 'm')
    {
        answer = num1 * num2;
        cout <<"Product: " << answer << endl;
    }//end if
    
    if (operation == 'D' || 'd')
    {    
        if (num1 > num2)
        {
            answer = num1 / num2;
        }//end if
        else
            answer = num2 / num1;
    
        cout <<"Quotient: " << answer << endl;
    }//end if

    return 0;
}//end of main function