How to manipulate the result of two parameters with arithmetic operations?

Question

Partially Solved

Check bellow to see how i solved this silly big problem.

---

I am currently trying to learn how to preform any mathematical operation (in the console) to the result of the previous mathematical operation, for example:

user inputs 1
            +
            2
            system("cls");
            3
            *
            2
            system("cls");
            6
            /
            2
            system("cls");
            3

so on and so forth.

Here is my code:

#include <iostream>
#include <string>
#include <windows.h>
using namespace std;

int main()
{
double num,num2, res;
string fchoice;
char choice;


system("cls");
cout << "0\b";
cin >> num;
system("cls");

cout << num << "\n\n";
cout << num << endl;
LOOP:
cin >> choice;
cout << "\n";

switch(choice)
    {
    case '+' :
        cin >> num2;
        res = num + num2 ;
                system("cls");
    cout << res << endl;
        break;

    case '-' :
        cin >> num2;
        res = num - num2 ;
                system("cls");
    cout << res << endl;
        break;
    case '/' :
        cin >> num2;
        res = num / num2 ;
                system("cls");
    cout << res << endl;
        break;
    case '*' :
        cin >> num2;
        res = num * num2 ;
                system("cls");
    cout << res << endl;
        break;
    }



return 0;
}

But the problem is, i don't know how to store the last result. So my questions are (if it's not too much trouble for you guys):

• How can i store the result so i can manipulate it later on?

• How to make the console reset (or delete) the previous results if the user enters a number and not an operation, and make the console ready to make new operations?

  If you guys could give me some hints, i'll thankful.

EDIT: I forgot to mention that am a beginner.

Last Edit:

All i had to do was simply add this line to rewrite the previously defined double num to num = res; just before the goto LOOP; so it would always return to the beginning.

Answer 1

You really should stop using goto statements and start using loops for this. (BTW I can see your label, but not your goto statement? ). To answer your second question, you could add a default statement in the switch statement, which will make it go back to the top if not an

 default:
    goto (any label at beginning of program);

Or if you were using a while loop, just clear all your values in the default statement.

As a footnote, why write the

cout<<res<<endl;

4 times? just write outside the switch once.