auto_ptr demo

smart_pointer.cc

// avoid resource leaks when exceptions are thrown.
//  if an exception occurs after successful memory allocation but 
// before the delete statement executes, a memory leak could occur. 
// void memory_leak() 
//{
//	ClassA * ptr = new ClassA;
//	try {
//	...
//	}
//	catch(...) {
//		delete ptr;
//		throw;
//	}
//	delete ptr;
//}

#include <iostream>
#include <memory>

using namespace std;

class Double {
 public:
  Double(double d = 0) : dValue(d) { cout << "constructor: " << dValue << endl; }
  ~Double() { cout << "destructor: " << dValue << endl; }
  void setDouble(double d) { dValue = d; }
 private:
  double dValue;
};


int main() {
  auto_ptr<Double> ptr(new Double(3.14));
  (*ptr).setDouble(6.28);
  return 0;
}