The following example demonstrates how you can establish a DDE channel to a Microsoft Excel worksheet named Sheet1. DDEAdvise( ) is used to establish two links to data in two worksheet cells (R1C1 and R1C2). The user-defined function NEWDATA is executed when data in either of the cells changes. The user-defined function tests the item and advise parameters to determine which item changed and what kind of link has been established.
PUBLIC mchannum
mchannum = DDEInitiate('Excel', 'Sheet1')
IF mchannum != -1
= DDEAdvise(mchannum, 'R1C1', 'newdata', 1) && Notify link
= DDEAdvise(mchannum, 'R1C2', 'newdata', 2) && Automatic link
WAIT WINDOW 'Enter data in first two cells in Excel.'
ENDIF
PROCEDURE newdata
PARAMETERS channel, action, item, data, format, advise
IF action = 'ADVISE'
DO CASE
CASE item = 'R1C1' && Notify link
newvalue = DDERequest(channel, item)
? 'R1C1 notify link: ' + newvalue
CASE item = 'R1C2' && Automatic link
newvalue = data
? 'R1C2 automatic link: ' + newvalue
ENDCASE
ELSE
IF action != "TERMINATE"
= DDETerminate(mchannum)
ENDIF
ENDIF