Listbox.Clear .Add Methods

[Halsafar]

Much like in VB, I figured I would need to create some fancy listbox functions for C++.


Here is one I cannot seem to get to work properly.

//------------------
//Add an item to the list
//------------------
void ListBox::AddItem(char* Item)
{
    //add string
    SendMessage(m_hwnd, LB_ADDSTRING, 0, (LPARAM)Item);
    SendMessage(m_hwnd, LB_SETITEMDATA, m_IndexCount, (LPARAM)m_IndexCount);
    m_IndexCount++;
}


//------------------
//Clear the entire list
//------------------
void ListBox::Clear()
{
    LRESULT lRet;
    for (int Index = 0; Index < m_IndexCount+1; Index++)
    {
        lRet = SendMessage(m_hwnd, LB_DELETESTRING, Index,0);
    }

    m_IndexCount = 0;
} 

So I add a bunch of strings using the Add function, then I try and clear it all.

Well now and then it clears all but one, sometimes all but two depending on how many I add. If it clears all but 1 or 2, or more..then I can just keep pressing it and it gets rid of everything one at a time.

What is going on????

[Trunks]

Instead of sending an LB_DELETESTRING message for each item, just send an LB_RESETCONTENT message.

[Halsafar]

You know, I scoured the list of messages, styles, notifications on MSDN for something like that and I just didn't see it.

Thank you, it all works fine now.

RemoveItem, AddItem, Clear...all work

[Halsafar]

Index is always 0...it never incrememnts, shouldnt it?
MSDN says that particular SendMessage returns the index of the added string.

//------------------
//Add an item to the list
//------------------
void ListBox::AddItem(char* Item)
{
    int Index=0;
    //add string
    Index = SendMessage(m_hwnd, LB_ADDSTRING, 0, (LPARAM)Item);
    SendMessage(m_hwnd, LB_SETITEMDATA, Index, (LPARAM)Item);
} 

[wey97]

Why are you adding an item to the list and then setting the text of the item again? The string would be there after LB_ADDSTRING.

Are you subclassing? That may be why it returns 0.

[Halsafar]

Yes I am subclassing, and it was the reason, fixed that part.

Now wuts wrong the above, I do see setting the string twice...thats just how I saw some code do it so each item had a proper index.

I guess though I don't really need any item data I found ways around all of that already.