[Cuchulainn]

Some exam questions on memory management, smart pointers. (Word 2003 and 2007).

[Cuchulainn]

Explain what is happening here:

// TestScopedPtr.cpp
//
// Testing scoped pointers in boost
//
// (C)Datasim Education BV 2008
//

#include "boost/scoped_ptr.hpp"
#include "Point.hpp"


int main()
{

{
// Create dynamic memory
boost::scoped_ptr <Point> myPoint (new Point(1.0, 23.3));

// Scoped pointer has same syntax as a raw pointer
if (myPoint != 0)
{
cout << *myPoint;
}

// Assign to another point
Point yourPoint (7.3, -9.9);

*myPoint = yourPoint;
cout << *myPoint;

// Use operator '->'
myPoint -> X(8. 6);
cout << *myPoint;

// Cannot assign scoped pointers, because operator '=' is private
boost::scoped_ptr <Point> myPoint2 (new Point(1.0, 23.3));
// THIS CODE DOES NOT COMPILE myPoint = myPoint2;

// Illegal, cannot convert
// boost::scoped_ptr <Point> illegalVar (new double);

}

return 0;
}

[Cuchulainn]

In C++ we use raw pointers; boost has functionality for smart pointers.

Questions:

1. What are the 3 largest potential pitfalls with raw pointers?
2. How does boost resolve these problems?
3. What is the difference between scoped pointers and auto_ptr? Which one to use and when?
4. Which boost smart pointers implements the Gamma (GOF) Flyweight pattern?
5. How to avoid dangling pointers?