SELECT test1
scan
c3 = ALLTRIM(LEFT(examcode ,3))
DO rep1 WITH c3
replace nmonth WITH cRes
ENDSCAN

I used the c3= examcode instead of c3 = ALLTRIM(LEFT(examcode ,3))

I get requaire result. Now i am going cheking manualy is my replacenet is true.please send your more advise on this