WINPRO MFC Collection class

8/7/2019 WINPRO MFC Collection class

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Windows programming

MFC collection class

Amarsanaa .G

School of Information Technology

National University of Mongolia


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MFC Collection class

A collection class is used to create objectsthat are capable of storing other objects.

Using a collection allows the programmer tohold, process, or store groups of class objectsor variables of certain standard types.

Three basic types of collection class: CArray, CList, CMap

Each is available in template and non-template version.

#include


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CArray class

A safe array and enables you to store and accessdata using subscript, or [ ] operator.

CArray consumes memory and time when growing or

attempting to store in the middle. If time is a factor then use a simple array instead

which does not grow dynamically.

Template class definition in header file:

template < class TYPE, class ARG_TYPE =const TYPE& > class CArray : publicCObject


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CList class

A linked list.

Supports ordered lists of nonunique objects

accessible sequentially or by value.

template< class TYPE, classARG_TYPE = const TYPE& > classCList : public CObject


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CMap class

A hash table.

A dictionary collection class that maps unique

keys to values. Key is converted into a hash value for use

as index to an array of collection items.

template< class KEY, class ARG_KEY,class VALUE, class ARG_VALUE>class CMap : public CObject


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Collection Shape Features

Article on msdn.microsoft.com: Recommendations for Choosing a Collection Class

http://msdn.microsoft.com/en-us/library/y1z022s1(VS.80).aspx, Mar 2009


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Types of CArray

The array collection classes are named forthe objects that they hold and are: CByteArray - BYTE values CWordArray - WORD values CDWordArray - DWORD values CPtrArray - void pointer values CObArray - class object pointers

CStringArray - CString objects CUIntArray - UINT values

These classes are non-template CByteArray class definition in

class CByteArray : public CObject


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Using CArray class

The member function 'SetAtGrow' stores anitem in the CArray at the specified position or

index. If the CArray is not large enough tohold, it expands to accommodate the newitem.

The member function 'SetAt' does the samebut does not increase the CArray sizeautomatically.

The member function 'GetSize' gives thenumber of items stored in the CArray.


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CArray membersAccessingtheArrayBounds

GetSize() Gets the number of elements in this array.GetUpperBound() Returns the largest valid index.SetSize() Sets the number of elements to be contained in this array.

OperationsFreeExtra() Frees all unused memory above the current upper bound.RemoveAll() Removes all the elements from this array.

ElementAccessGetAt() Returns the value at a given index.SetAt() Sets the value for a given index; array not allowed to grow.ElementAt() Returns a temporary reference to the element pointerwithin the array.

GrowingtheArraySetAtGrow() Sets the value for a given index; grows the array ifnecessary.Add() Adds an element to the end of the array; grows the array ifnecessary.

Insertion/RemovalInsertAt() Inserts an element (or all the elements in another array) ata specified index.RemoveAt() Removes an element at a specific index.

Operatorsoperator [] Sets or gets the element at the specified index.


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Example of CArray

#include // for using MFC class CString in a console type

app.#include #include // for use of any MFC collection classesint main(){

CArray rgSports;// The first parameter represents the type ofobject stored inside the list, the next// parameter is the type of object passed as anargument for CArray functions

// Define the objects.CString szBaseball("Baseball - NY Yankees");CString szSoccer("Soccer - NY Giants");CString szCricket("Cricket - South Africa");CString szHockey("Hockey - Korea");

CString szBasketball("Baseball - Celtics");


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Example of CArray

// Add five teams to the rgSports array. The firstparameter becomes the index and

// the second CString name , the reference to it willbe passed.

rgSports.SetAtGrow(0, szBaseball);rgSports.SetAtGrow(1, szSoccer);rgSports.SetAtGrow(0, szCricket);rgSports.SetAtGrow(0, szHockey);rgSports.SetAtGrow(0, szBasketball);

// Display the contents of the Sports array.cout


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MemoryType of array CString

Baseball - NY Yankees

Soccer - NY Giants

Cricket - South Africa

Hockey- Korea

Baseball - Celtics

rgSports[0]

rgSports[1]

rgSports[2]

rgSports[3]

rgSports[4]

Memory type: CString object


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Output of Example


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WINPRO MFC Collection class

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