MFC Collection Classes: Arrays, Linked Lists, and Maps, Study notes of Object Oriented Programming

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MFC Collection Classes

References

 This material is drawn from “Programming

Windows with MFC”, 2nd Edition, Jeff Prosise,

Microsoft Press, 1999, Chapter 5

 This presentation is adapted from one

presented by Pei Lin and Huan-Tang Yang,

Summer 2001

Goals

• Introduce MFC collection classes.

• Describe common usage

• List member functions to serve as a quick

reference.

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.

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 (DWORD

s)

CStringList CMapPtrToPtr

CUIntArray (UINTs) CMapWordToOb

CStringArray (CStrings

CMapStringToOb

CPtrArray (void

pointers)

CMapStringToPtr

CObArray (CObject

ptrs)

CMapStringToString

MFC Array Classes

(A checkmark  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.

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.

Member functions

 (^) SetAt( int nIndex, ARG_TYPE newElement )  (^) GetAt( int nIndex )  (^) GetSize()  (^) GetUpperBound()  (^) RemoveAt( int nIndex, int nCount = 1 )  (^) RemoveAll( )

DynamicArraySizing

Functions

• SetSize()

• SetAtGrow()

• Add ()

• InsertAt ()

MFC List Classes

• Doubly linked lists for fast item insertion and

removal

• POSITION type:

A pointer to a CNode data structure (a list

item)

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.

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

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