After introduction of weekly options for banknifty, in instruments list symbol formation is not consistent for banknifty all options which makes it very difficult to process using regular expressions.
@Kailash Your update related to BankNifty is little bit friendly , but there are two different format for BankNifty Options symbol , one is with full date like ' BANKNIFTY09JUN1619300CE' and another is for last week of month 'BANKNIFTY16JUN19100CE' , so can you make a single format for this ?