/* The following code example is taken from the book
* "C++ Templates - The Complete Guide"
* by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
*
* (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include
#include
template
class ObjectCounter {
private:
static size_t count; // number of existing objects
protected:
// default constructor
ObjectCounter() {
++count;
}
// copy constructor
ObjectCounter (ObjectCounter const&) {
++count;
}
// destructor
~ObjectCounter() {
--count;
}
public:
// return number of existing objects:
static size_t live() {
return count;
}
};
// initialize counter with zero
template
size_t ObjectCounter::count = 0;
template
class MyString : public ObjectCounter > {
//...
};
int main()
{
MyString s1, s2;
MyString ws;
std::cout << "number of MyString: "
<< MyString::live() << std::endl;
std::cout << "number of MyString: "
<< ws.live() << std::endl;
}
number of MyString: 2
number of MyString: 1