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Thinking in C++
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Solutions to selected exercises can be found in the electronic document The Thinking in C++ Annotated Solution Guide, available for a small fee from

  1. Create a class Counted that contains an int id and a static int count. The default constructor should begin:
    Counted( ) : id(count++) {. It should also print its id and that it’s being created. The destructor should print that it’s being destroyed and its id. Test your class.
  2. Prove to yourself that new and delete always call the constructors and destructors by creating an object of class Counted (from Exercise 1) with new and destroying it with delete. Also create and destroy an array of these objects on the heap.
  3. Create a PStash object and fill it with new objects from Exercise 1. Observe what happens when this PStash object goes out of scope and its destructor is called.
  4. Create a vector< Counted*> and fill it with pointers to new Counted objects (from Exercise 1). Move through the vector and print the Counted objects, then move through again and delete each one.
  5. Repeat Exercise 4, but add a member function f( ) to Counted that prints a message. Move through the vector and call f( ) for each object.
  6. Repeat Exercise 5 using a PStash.
  7. Repeat Exercise 5 using Stack4.h from Chapter 9.
  8. Dynamically create an array of objects of class Counted (from Exercise 1). Call delete for the resulting pointer, without the square brackets. Explain the results.
  9. Create an object of class Counted (from Exercise 1) using new, cast the resulting pointer to a void*, and delete that. Explain the results.
  10. Execute NewHandler.cpp on your machine to see the resulting count. Calculate the amount of free store available for your program.
  11. Create a class with an overloaded operator new and delete, both the single-object versions and the array versions. Demonstrate that both versions work.
  12. Devise a test for Framis.cpp to show yourself approximately how much faster the custom new and delete run than the global new and delete.
  13. Modify NoMemory.cpp so that it contains an array of int and so that it actually allocates memory instead of throwing bad_alloc. In main( ), set up a while loop like the one in NewHandler.cpp to run out of memory and see what happens if your operator new does not test to see if the memory is successfully allocated. Then add the check to your operator new and throw bad_alloc.
  14. Create a class with a placement new with a second argument of type string. The class should contain a static vector<string> where the second new argument is stored. The placement new should allocate storage as normal. In main( ), make calls to your placement new with string arguments that describe the calls (you may want to use the preprocessor’s __FILE__ and __LINE__ macros).
  15. Modify ArrayOperatorNew.cpp by adding a static vector<Widget*> that adds each Widget address that is allocated in operator new( ) and removes it when it is released via operator delete( ). (You may need to look up information about vector in your Standard C++ Library documentation or in the 2nd volume of this book, available at the Web site.) Create a second class called MemoryChecker that has a destructor that prints out the number of Widget pointers in your vector. Create a program with a single global instance of MemoryChecker and in main( ), dynamically allocate and destroy several objects and arrays of Widget. Show that MemoryChecker reveals memory leaks.

[50] There is a special syntax called placement new that allows you to call a constructor for a pre-allocated piece of memory. This is introduced later in the chapter.

Thinking in C++
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   Reproduced courtesy of Bruce Eckel, MindView, Inc. Design by Interspire