poj 1488 TEX Quotes

//这题主要是两种左右引号比较难分清楚，只要将样例的copy下来，再通过键盘的尝试就容易得出！ 
#include <iostream>
#include <string>
using namespace std;

int main()
{
    int len, i;
    string str;
    bool flag = true; 
    while (getline(cin, str)){
          len = str.length();
          for (i = 0; i < len; i++){
              if (str[i] == '"' && flag == true){ 
                  cout << "``";
                  flag = false; 
              } 
              else if (str[i] == '"' && flag == false){
                   cout << "''";
                   flag = true; 
              } 
              else
                  cout << str[i];
          }
          cout << endl;
    }
    
    system("pause");
}

/*
"To be or not to be," quoth the Bard, "that
is the question".
The programming contestant replied: "I must disagree.
To `C' or not to `C', that is The Question!"
``To be or not to be,'' quoth the Bard, ``that
is the question''.
The programming contestant replied: ``I must disagree.
To `C' or not to `C', that is The Question!'' 
*/