小技巧，使用CArray——Using CArray

CArray的定义是：

template<class TYPE, class ARG_TYPE = const TYPE&>class CArray : public CObject{ // ....};

Parameters

TYPE

Template parameter specifying the type of objects stored in the array. TYPE is a parameter that is returned by CArray.

ARG _ TYPE

Template parameter specifying the argument type used to access objects stored in the array. Often a reference to TYPE. ARG_TYPE is a parameter that is passed to CArray.

 Remarks

Array indexes always start at position 0. You can decide whether to fix the upper bound or allow the array to expand when you add elements past the current bound. Memory is allocated contiguously to the upper bound, even if some elements are null.

As with a C array, the access time for a CArray indexed element is constant and is independent of the array size.

Tip

Before using an array, use SetSize to establish its size and allocate memory for it. If you do not use SetSize, adding elements to your array causes it to be frequently reallocated and copied. Frequent reallocation and copying are inefficient and can fragment memory.

If you need a dump of individual elements in an array, you must set the depth of the CDumpContext object to 1 or greater.

Certain member functions of this class call global helper functions that must be customized for most uses of the CArray class. See the topic Collection Class Helpers in the MFC Macros and Globals section.

Array class derivation is similar to list derivation.

For more information on using CArray, see the article Collections.

 

 

有个小技巧是可以这样使用:

 

typedefCArray<CTest, CTest &>CTestArray;class CTestContainer : public CTestArray{ //.............};

 

完整的CArray定义如下：

 

 template<class TYPE, class ARG_TYPE = const TYPE&>class CArray : public CObject{public:// ConstructionCArray();// AttributesINT_PTR GetSize() const;INT_PTR GetCount() const;BOOL IsEmpty() const;INT_PTR GetUpperBound() const;void SetSize(INT_PTR nNewSize, INT_PTR nGrowBy = -1);// Operations// Clean upvoid FreeExtra();void RemoveAll();// Accessing elementsconst TYPE& GetAt(INT_PTR nIndex) const;TYPE& GetAt(INT_PTR nIndex);void SetAt(INT_PTR nIndex, ARG_TYPE newElement);const TYPE& ElementAt(INT_PTR nIndex) const;TYPE& ElementAt(INT_PTR nIndex);// Direct Access to the element data (may return NULL)const TYPE* GetData() const;TYPE* GetData();// Potentially growing the arrayvoid SetAtGrow(INT_PTR nIndex, ARG_TYPE newElement);INT_PTR Add(ARG_TYPE newElement);INT_PTR Append(const CArray& src);void Copy(const CArray& src);// overloaded operator helpersconst TYPE& operator[](INT_PTR nIndex) const;TYPE& operator[](INT_PTR nIndex);// Operations that move elements aroundvoid InsertAt(INT_PTR nIndex, ARG_TYPE newElement, INT_PTR nCount = 1);void RemoveAt(INT_PTR nIndex, INT_PTR nCount = 1);void InsertAt(INT_PTR nStartIndex, CArray* pNewArray);// Implementationprotected:TYPE* m_pData; // the actual array of dataINT_PTR m_nSize; // # of elements (upperBound - 1)INT_PTR m_nMaxSize; // max allocatedINT_PTR m_nGrowBy; // grow amountpublic:~CArray();void Serialize(CArchive&);#ifdef _DEBUGvoid Dump(CDumpContext&) const;void AssertValid() const;#endif};

 

 

CArray

Constructs an empty array.

Attributes

GetCount

Gets the number of elements in this array.

GetSize

Gets the number of elements in this array.

GetUpperBound

Returns the largest valid index.

IsEmpty

Determines whether the array is empty.

SetSize

Sets the number of elements to be contained in this array.

Operations

FreeExtra

Frees all unused memory above the current upper bound.

RemoveAll

Removes all the elements from this array.

RelocateElements

Relocates data to a new buffer when the array should grow or shrink.

Element Access

ElementAt

Returns a temporary reference to the element pointer within the array.

GetAt

Returns the value at a given index.

GetData

Allows access to elements in the array. Can be NULL.

SetAt

Sets the value for a given index; array not allowed to grow.

Growing the Array

Add

Adds an element to the end of the array; grows the array if necessary.

Append

Appends another array to the array; grows the array if necessary

Copy

Copies another array to the array; grows the array if necessary.

SetAtGrow

Sets the value for a given index; grows the array if necessary.

Insertion/Removal

InsertAt

Inserts an element (or all the elements in another array) at a specified index.

RemoveAt

Removes an element at a specific index.

Operators

operator []

Sets or gets the element at the specified index.