[C++] fstream 中的! operator …

雖然已經學過，但是重新複習的時候，突然覺得fstream file ; if(!file) … 很神奇！就手癢做一個簡單版的。

http://gist.github.com/95100

/* Usage: To implement a object as fstream with operator ! and open()
*  Author: Allen (allen501pc@hotmail.com)
*  Date: 04/14/2009
*  Output:
*          object has been opened!
*/

#include <iostream>
using namespace std;
class object
{
  private:
      bool isset;
      bool notopen;
  public:
      object()
      {
          isset=false;
          notopen=true; /* Set it is not opened! */
      }
      bool operator!(); /* ! operator for checking open or not */
      void open()
      {
          notopen=false; /* set it is opened */
      }
};
/* operator ! for checking that opened or not
*  if open, return false
*  Or, return true
*/
bool object::operator!()
{
  return this->notopen;
}

int main(int argc,char * argv[])
{
  object ob; /* take class object as ob */
  ob.open(); /* open */
  if(!ob)
  {
      cout << "object has not been opened! " << endl;
  }
  else
      cout << "object has been opened! " << endl;
  return 0;
}