tree controls

[Toe]

I'm trying to use a tree control in c++ using an example from a book.

I can understand that the 'InsertItem' method called with a litteral string creates a node with that litteral string as a tag. (eg. aTree.InsertItem("Fred&quot creates a fred node). however, I don't (fully) understand the following code the book uses to create a list of A - Z tags:

for (int nChar='A';nChar<='Z'; nChar++)
hLetter[nChar - 'A'] =m_treeFiles.InsertItem((TCHAR*)&nChar);

This would appear to me (in my blissful ignorance) to be creating a node whose label is a pointer to the variable nChar.

how come (at the end of the procedure) these aren't all the same - ie. 'Z'??


(I'm really new to c++ abd just stuggeling to get to grips with microsoft visual c++ 6.0 so please excuse dumb questions!!)

 

[Zyrenthian]

What this is doing is inserting each letter of the alphabet into the tree. The insertItem function call returns the actual index it was inserted at. What I assume hLetter is, is a predefined member variable as
int hLetter[26];

what this provides is if you want to get access to the letter 'B' in the tree to set the current selection or what have you, you can just do

m_treeFiles.SetCurSel(hLetter['B'-'A']);

this can be made easier by passing in the character in an argument and adjusting it as follows

m_treeFiles.SetCurSel(hLetter[charVar - 'A']);


Matt