The Count property counts the columns in the collection. Use the Columns property to access the control's Columns collection. Use the Item property to access a column by its index or key. Use the Add method to add new columns to the control. Use the Remove method to remove a column. Use the Clear method to clear the columns collection. 

The following VB sample enumerates the columns in the control:

For Each c In Tree1.Columns
    Debug.Print c.Caption
Next

The following VB sample enumerates the columns in the control:

For i = 0 To Tree1.Columns.Count - 1
    Debug.Print Tree1.Columns(i).Caption
Next

The following VC sample enumerates the columns in the control:

#include "Columns.h"
#include "Column.h"
CColumns columns = m_tree.GetColumns();
for ( long i = 0; i < columns.GetCount(); i++ )
{
	CColumn column = columns.GetItem( COleVariant( i ) );
	OutputDebugString( column.GetCaption() );
}

The following VB.NET sample enumerates the columns in the control:

With AxTree1.Columns
    Dim i As Integer
    For i = 0 To .Count - 1
        Debug.WriteLine(.Item(i).Caption)
    Next
End With

The following C# sample enumerates the columns in the control:

EXTREELib.Columns columns =axTree1.Columns;
for ( int i = 0; i < columns.Count; i++ )
{
	EXTREELib.Column column = columns[i];
	System.Diagnostics.Debug.WriteLine( column.Caption );
}

The following VFP sample enumerates the columns in the control:

with thisform.Tree1.Columns
	for i = 0 to .Count - 1
		wait window nowait .Item(i).Caption
	next
endwith