코난도일의 자유로이~!

#include <iostream>
#include <string>

using namespace std;

class NoOrderOfOperations
{
public:

 int evaluate(string expr)
 {
   int len, i, result;
 char op;

 len = expr.size();

 result = expr[0] - '0';

 for(i = 1; i < len; i++ )
 {

  if(expr[i] >= '0' && expr[i] <= '9')
  {

   if(op == '+')
    result += expr[i] - '0';
   if(op == '-')
    result -= expr[i] - '0';
   if(op == '*')
    result *= (expr[i] - '0');
   if(op == '/')
    result /= (expr[i] - '0');
  }
  else if(expr[i] == '+' || expr[i] == '-' || expr[i] == '*' || expr[i] == '/')
    op = expr[i];
 }

 return result;
 }
};