Expression For Extract A Substring from the given String In SSIS

Expression For Extract A Substring from the given String

Expression:-
SUBSTRING( @[User::strPackageName] , FINDSTRING( @[User::strPackageName] , "ETL_Extract",1) + 12 , LEN( @[User::strPackageName] ) )

VB.NET Code:-
Dts.Variables("strPkgName").Value = Mid(Dts.Variables("strPackageName").Value.ToString, InStrRev(Dts.Variables("strPackageName").Value.ToString, "\", -1) + 1, Len(Dts.Variables("strPackageName").Value.ToString))