C++ calculator that loops answers

[aaguilar2021]

I am trying to code a calculator that uses the result of the previous calculation as one of the inputs for the next calculation. However, when I run the code, it keeps telling me that lvalue is required as the left operand of the assignment, with the compiler telling me that the "/" in line 18 is the problem. Any corrections would be greatly appreciated.

  #include <iostream>
#include <string>
using namespace std;
int result;
int value;
char sign;
int main()
{
    result = 0;
    // Loop forever (or till we hit the break statement)
    do
    {
        cout << "Current value is " << result << endl;
        cout << "Please enter an operation +, -, *, / <'Q' to quit>: ";
        cin >> sign;
        cout << "Please enter a number: ";
        cin >> value;
        if (sign = '+' || sign = '-' || sign = '*' || sign = '/')
        {
            if (sign = '+')
            {
                result += value;
            }
            else if (sign = '-')
            {
                result -= value;
            }
            else if (sign = '*')
            {
                result *= value;
            }
            else if (sign = '/')
            {                result /= value;
            }  
        }
        else if (sign = 'q')
        {
            break;
        }
        else
        {
            cout << "Unknown operator " << sign << endl;
        }
    }while(1);
    return 0;
}

[salem c]

> if (sign = '+' || sign = '-' || sign = '*' || sign = '/')
Use ==, not = for comparing.

And put all your globals inside main.

int main ( ) {
  int result;
  int value;
  char sign;
.. etc

[lastchance]

"=" = "becomes"
"==" = equals