Use C ++ SDK to implement dynamic array classes

C ++ SDK does not directly provide the dynamic array function. Although it can be implemented using the carray class of MFC or using the pointer + new, the former requires the MFC library, the latter is hard to understand and inefficient. Therefore, I have posted a simple dynamic array class I wrote a long time ago, hoping to inspire some friends.

Code Description: This class is optimized in the assignment of array members and memory allocation, significantly improving the performance of large arrays.

Usage: copy the code to the header file cmyarray. h and reference the file in the project.

I. header file cmyarray. h

# Ifndef _ tdarray_h __# DEFINE _ tdarray_h __# include <windows. h> # include <tchar. h> template <typename T> class cmyarray {PRIVATE: T * m_parray; // memory pointer DWORD m_nitemcount; // Total Number of Members DWORD m_nblockcount; // Number of memory blocks DWORD m_nitemsperblock; // Number of Members contained in each memory block DWORD m_dwallocationgranularity; // memory allocation granularity (I .e. memory block size) DWORD item_size; public: cmyarray () {system_info Si; getsysteminfo (& Si); m_dwallocationgranularity = SI. dwallocationgra Nularity; m_nitemcount = 0; m_nblockcount = 0; m_parray = NULL; item_size = sizeof (t); m_nitemsperblock = m_dwallocationgranularity/item_size ;};~ Cmyarray () {If (m_parray) globalfree (m_parray) ;}; T * Add (T item) {return add (& item) ;}; T * Add (T * item) {If (! M_parray) {m_parray = (T *) globalalloc (gmem_fixed | gmem_zeroinit, m_dwallocationgranularity); If (! M_parray) Throw _ T ("memory overflow"); m_nblockcount = 1;} else {If (m_nitemcount % m_nitemsperblock = 0) {m_nblockcount ++; m_parray = (T *) globalrealloc (m_parray, m_nblockcount * m_dwallocationgranularity, gmem_moveable | gmem_zeroinit); If (! M_parray) Throw _ T ("memory overflow") ;}} T * P = m_parray + m_nitemcount; If (item_size <= 8) * P = * item; elsememcpy (p, item, item_size); m_nitemcount ++; return P ;}; bool remove (DWORD position) {If (position <m_nItemCount-1) {memcpy (m_parray + position, m_parray + Position + 1, (m_nItemCount-1-position) * item_size); m_nitemcount --; return true;} return false;}; void clear () {If (m_parray) globalfree (m_parray); m_nitemcount = 0; m_nblockcount = 0; m_parray = NULL;}; T * getitem (DWORD position) {If (position <m_nitemcount) return m_parray + position; elsereturn NULL;}; t getitemvalue (DWORD position) {return * (m_parray + position) ;}; bool setitem (DWORD position, t item) {return setitem (Position, & item) ;}; bool setitem (DWORD position, T * Item) {If (position <m_nitemcount) {T * P = m_parray + position; if (item_size <= 8) * P = * item; elsememcpy (, item, item_size); Return true;} return false;}; DWORD getcount () {return m_nitemcount ;};## endif/_ tdarray_h __

Ii. Test code:

# Include "stdafx. H "# include <stdio. h> # include <dos. h> # include <conio. h> # include "cmyarray. H "int main (void) {long I; // instantiate the array class cmyarray <long> * parray = new cmyarray <long> (); // Add an array member for (I = 1; I <100000; I ++) {parray-> Add (I );} // remove the array member parray-> remove (99991); // obtain the number of array members long ncount = parray-> getcount (); // display part of the array member for (I = 99990; I <ncount; I ++) {printf ("member % d value: % d. \ R \ n ", I, parray-> getitemvalue (I);} // destroy the array object Delete parray; getchar (); Return 0 ;}