Need help in method parameter type.

Question

Hi all,

i have a method say for student fee collection, in that there are three parameter studid,feeamount, collection date. method defination is like below.

public string CollectFee(string studentid, decimal feeamount, DateTime collectiondate)

{

}

In this while calling this method from presentation layer..user must have to have enter all the parameter if any of the parameter is missing he will get message like....studentid and feeamount and  collection date is required. i want to check these while impleting the CollectFee method, since the method parameter having string, decimal, datetime datatype, how can i check empty or not for these in one if condition.