Just wondering if anyone knows how to fix this error? I\'ve also used TypeCode. but still no luck. Thanks
case typeof(Nullable).ToString
Ultimately, typeof(Nullable<int>) isn't a TypeCode, and the string representation of that isn't a TypeCode. There is no TypeCode that represents Nullable<int> specifically.
You can use Nullable.GetUnderlyingType(type) to check that something is Nullable<T> and get the T at the same time (it returns null if not), and you can use Type.GetTypeCode on the result of that, but: I suspect that in your case, using TypeCode at all may be an error, and simply checking the type itself (if (type == typeof(int?)) {...}) may be better.
The type you use in the switch statement has to match the type in the case statements, where currently you're comparing a TypeCode to a string.
The TypeCode enumeration only contains values for the primitive types, and all others will be TypeCode.Object. So you can't get a specific TypeCode for the Nullable<int> type.