Sorted MFC CArray
·2 min read·paskov
Update: An updated version of CSortArray is now available.
While working on a project in my spare time, I needed a quick way to sort elements stored in an MFC CArray. I wrote CSortArray, which extends CArray with a public QuickSort() method that uses the C runtime’s qsort function.
Here’s the class:
#include <afxtempl.h>
#include <stdlib.h>
template <class TYPE, class ARG_TYPE = const TYPE&>
class CSortArray : public CArray<TYPE, ARG_TYPE>
{
public:
void QuickSort(int (__cdecl *compare)(const void*, const void*))
{
qsort(this->m_pData, this->GetCount(), sizeof(TYPE), compare);
}
};The QuickSort() method takes a pointer to a comparison function with this signature:
int Compare(const void* pElement1, const void* pElement2);pElement1 and pElement2 point to the two elements being compared. The function must return:
- A value less than
0ifpElement1is less thanpElement2. 0if the elements are equal.- A value greater than
0ifpElement1is greater thanpElement2.
Save the class in SortArray.h. The following MFC console example sorts an array of integers:
#include "stdafx.h"
#include "SortArray.h"
#include <iostream>
using namespace std;
// Comparison function for integer elements.
int Compare(const void* element1, const void* element2)
{
const int* pElem1 = static_cast<const int*>(element1);
const int* pElem2 = static_cast<const int*>(element2);
if (*pElem1 < *pElem2)
{
return -1;
}
else if (*pElem1 == *pElem2)
{
return 0;
}
else
{
return 1;
}
}
// Application entry point.
int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
CSortArray<int> arrToSort;
// Add some unsorted elements to the array.
arrToSort.Add(5);
arrToSort.Add(2);
arrToSort.Add(10);
arrToSort.Add(17);
arrToSort.Add(1);
arrToSort.Add(8);
arrToSort.Add(3);
// Display the unsorted elements.
cout << "Unsorted elements" << endl;
for (int i = 0; i < arrToSort.GetCount(); i++)
{
cout << arrToSort[i] << endl;
}
// Sort the array.
arrToSort.QuickSort(Compare);
// Display the sorted elements.
cout << "Sorted elements" << endl;
for (int j = 0; j < arrToSort.GetCount(); j++)
{
cout << arrToSort[j] << endl;
}
return 0;
}CSortArray could also provide a search method, but that’s a topic for another post.