1. MFC Collection Classes
Jim Fawcett
CSE 791 – Advanced Windows Programming
Summer 2002

2. Topics MFC collection classes – Arrays – Linked lists – maps
Description
Class member functions.
Demo applications

3. Goals Introduce MFC collection classes. Describe common usage
List member functions to serve as a quick reference.

4. Motivation To gain extra power over data in your programs
bounds-checking and handling
Change size dynamically – provides run-time flexibility
To simplify many operations involving use of complex data structures
Compare to STL classes in MFC applications
VC++ Ver 6.0 is not thread-safe. Much of MFC is multi-threaded
using MFC collection classes will avoid your application linking to two separate class libraries.

5. Classification – by type
MFC template-based collection classes - Defined in Afxtempl.h
Syntax example:
CArray< class TYPE, class ARG_TYPE > myArray;
CTypedPtrList<class BASE_CLASS, class TYPE> myList;
Content
Arrays
Lists
Maps
Type-safe objects
CArray
CList
CMap
Type-safe pointers to objects
CTypedPtrArray
CTypedPtrList
CTypedPtrMap

6. Classification – by type
MFC collection classes not based on templates - Defined in Afxcoll.h
Arrays
Lists
Maps
CByteArray (BYTEs)
CObList
CMapWordToPtr
CWordArray(WORDs)
CPtrList
CMapPtrToWord
CDWordArray(DWORDs)
CStringList
CMapPtrToPtr
CUIntArray (UINTs)
CMapWordToOb
CStringArray(CStrings)
CMapStringToOb
CPtrArray (void pointers)
CMapStringToPtr
CObArray(CObject ptrs)
CMapStringToString

7. MFC Array Classes (A checkmark a indicates that function can grow dynamically.)
Member Functions of the Array Classes:
Add( ) Appends a value to the end of the array, increasing the size of the array as needed.
ElementAt( ) Gets a reference to an array element’s pointer.
FreeExtra( ) Releases unused array memory.
GetAt( ) Gets the value at the specified array index.
GetSize( ) Gets the number of elements in the array.
GetUpperBound( ) Gets the array's upper bound, which is the highest valid index at which a value can be stored.
InsertAt( ) Inserts a value at the specified index, shifting existing elements upward as necessary to accommodate the insert.

8. Member Functions of the Array Classes
RemoveAll( ) Removes all of the array's elements.
RemoveAt( ) Removes the value at the specified index.
SetAt( ) Places a value at the specified index. Because this function will not increase the size of the array, the index must be currently valid.
SetAtGrow( ) Places a value at the specified index, increasing the size of the array as needed.
SetSize( ) Sets the array's size, which is the number of elements that the array can hold. The array still can grow dynamically beyond this size.
Append( ) Appends one array to another
Copy( ) Copies one array to another

9. How much it will grow?
You can use setSize method to specify how big you want the array grow each time.
If you don’t, MFC picks one for you using a simple formula based on the array size. The larger the array, the larger the grow size.
The default grow size is 4 items.

10. Member functions SetAt( int nIndex, ARG_TYPE newElement )
GetAt( int nIndex )
GetSize()
GetUpperBound()
RemoveAt( int nIndex, int nCount = 1 )
RemoveAll( )

11. RemoveAll ( )
If the elements are pointers,the remove functions delete elements, but they don't delete objects that the elements point to.
You should do this :
int nSize = array.GetSize ();
for (int i=0; i<nSize; i++)
delete array[i];
array.RemoveAll (); //delete objects first !!

12. DynamicArraySizing Functions
SetSize()
SetAtGrow()
Add ()
InsertAt ()

13. MFC List Classes
Doubly linked lists for fast item insertion and removal
POSITION type: A pointer to a CNode data structure (a list item)

14. Member Functions of list Classes
AddHead( ) Adds a node to the head of the list, making the node the new head.
AddTail( ) Adds a node to the tail of the list, making the node the new tail.
Find( ) Searches the list sequentially to find the given object pointer. Returns a POSITION value.
FindIndex() Scans list sequentially, stopping at node indicated by the given index. Returns a POSITION value for the node.
GetAt( ) Gets the node at the specified position.
GetCount( ) Gets the number of nodes in the list.
GetHead( ) Gets the list's head node.
GetHeadPosition( ) Gets the head node's position.

15. Member Functions of List Classes
GetNext( ) When iterating over list, gets next node.
GetPrev( ) When iterating over list, gets previous node.
GetTail( ) Gets the list's tail node.
GetTailPosition( ) Gets the tail node's position.
InsertAfter( ) Inserts a new node after the specified position.
InsertBefore( ) Inserts a new node before the specified position.
IsEmpty( ) Returns TRUE if list is empty and returns FALSE otherwise.
RemoveAll( ) Removes all of a list's nodes.
RemoveAt( ) Removes a single node from a list.
RemoveHead( ) Removes the list's head node.
RemoveTail( ) Removes the list's tail node.
SetAt( ) Sets the node at the specified position.

16. Caution
In Clist:
If you use Find function, you should overload operator ==
Or you can overload template function "CompareElements“
CPoint and CString have overloaded operator ==

17. MFC MAP Classes What is a map? How do Maps work?
A table of items keyed by other items.
How do Maps work?
Implemented by Hash Table so not sorted
Fast searching on key type

18. Member Functions of map Classes
GetCount( ) Gets the number of map elements
GetNextAssoc( ) When iterating over the map, gets the next element
GetStartPosition( ) Gets the first element's position
IsEmpty( ) Returns TRUE if the map is empty and returns FALSE otherwise
Lookup( ) Finds the value associated with a key
RemoveAll( ) Removes all of the map's elements
RemoveKey( ) Removes an element from map
SetAt( ) Adds map element or replaces element with matching key