Sort - worked example

key : purple - original code / blue - new code

Step 1 :

Continue with the program names.

Step 2 :

Give the columns names. Define these in the header. This makes working with the columns easier and more readable :

// column order - remember to change column text
const int COLUMN_TITLE = 1;
const int COLUMN_FIRST_NAME = 2;
const int COLUMN_SECOND_NAME = 0;

and in the original definition :

// COLUMN_TITLE is a const int defined in the header
listColumn.iSubItem = COLUMN_TITLE;
listColumn.pszText = arColumns[COLUMN_TITLE];
m_listCtrl.InsertColumn( COLUMN_TITLE, &listColumn );

listColumn.iSubItem = COLUMN_FIRST_NAME;
listColumn.pszText = arColumns[COLUMN_FIRST_NAME];
m_listCtrl.InsertColumn( COLUMN_FIRST_NAME, &listColumn );

listColumn.iSubItem = COLUMN_SECOND_NAME;
listColumn.pszText = arColumns[COLUMN_SECOND_NAME];
m_listCtrl.InsertColumn( COLUMN_SECOND_NAME, &listColumn );

and so on

Step 3 :

Add the LVN_COLUMNCLICK windows message handler to the ListCtrl :

void CNameListView::OnColumnClick(NMHDR* pNMHDR, LRESULT* pResult)
{

NM_LISTVIEW* pNMListView = (NM_LISTVIEW*)pNMHDR;

*pResult = 0;

}

Step 4 :

Add bitwise constants for the combinations :

const int TITLE_BIT = 1;
const int FIRST_NAME_BIT = 2;
const int SECOND_NAME_BIT = 4;
const int ASC_BIT = 8;
const int DESC_BIT = 16;

Step 6 :

Add new code to the OnColumnClick() function :

void CNameListView::OnColumnClick(NMHDR* pNMHDR, LRESULT* pResult)
{

NM_LISTVIEW* pNMListView = (NM_LISTVIEW*)pNMHDR;

CListCtrl& m_listCtrl = GetListCtrl();

int nColumn = pNMListView->iSubItem;
UINT dwData;

// this is a good example of how the bit operator works!!!

static int nCountTitle = 1;
static int nCountFirstName = 1;
static int nCountSecondName = 1;

if( nColumn == COLUMN_TITLE )
{

if(nCountTitle%2 == 1)
{

dwData = TITLE_BIT | ASC_BIT;

}
else
{

dwData = TITLE_BIT | DESC_BIT;

}
// increment this column count - reset the other column counts
nCountTitle++;
nCountFirstName = 1;
nCountSecondName = 1;

}

if( nColumn == COLUMN_FIRST_NAME )
{

if(nCountFirstName%2 == 1)
{

dwData = FIRST_NAME_BIT | ASC_BIT;

}
else
{

dwData = FIRST_NAME_BIT | DESC_BIT;

}
nCountFirstName++;
nCountTitle = 1;
nCountSecondName = 1;

}

if( nColumn == COLUMN_SECOND_NAME )
{

if(nCountSecondName%2 == 1)
{

dwData = SECOND_NAME_BIT | ASC_BIT;

}
else
{

dwData = SECOND_NAME_BIT | DESC_BIT;

}
nCountSecondName++;
nCountTitle = 1;
nCountFirstName = 1;

}

m_listCtrl.SortItems( CompareFunction, dwData );

*pResult = 0;

}

Step 7 :

Add a function to sort the data in the columns :

vint CALLBACK CNameListView::CompareFunction
(LPARAM lParam1, LPARAM lParam2, LPARAM lParamSort)
{

CName * pName1 = (CName *)lParam1;
CName * pName2 = (CName *)lParam2;

if( lParamSort & TITLE_BIT )
{

CString strName1 = pName1->GetTitle();
CString strName2 = pName2->GetTitle();
if ( lParamSort & ASC_BIT)
return strcmp(strName1, strName2);
else
return strcmp(strName2, strName1);

}
else if( lParamSort & FIRST_NAME_BIT )
{

CString strName1 = pName1->GetFirstName();
CString strName2 = pName2->GetFirstName();
if ( lParamSort & ASC_BIT)
return strcmp(strName1, strName2);
else
return strcmp(strName2, strName1);

}
else if( lParamSort & SECOND_NAME_BIT )
{

CString strName1 = pName1->GetSecondName();
CString strName2 = pName2->GetSecondName();
if ( lParamSort & ASC_BIT)
return strcmp(strName1, strName2);
else
return strcmp(strName2, strName1);

}
else
return 1;

}

Click here for the basic exercise

Click here for the source code

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