不可发音成员'xyz'不能像方法一样使用，vb和c＃之间的区别

Question

I have this code in VB:

Private mTemmpEmpTimesheetDeclareDetails As IEnumerable(Of 
EmpTimesheetDeclareDetail) = Nothing

If mTemmpEmpTimesheetDeclareDetails.Count > 0 Then
mEmpTimesheetDeclareDetail = mTemmpEmpTimesheetDeclareDetails(0)
End If

Now i have converted the same piece of code in c#:

private IEnumerable<EmpTimesheetDeclareDetail> mTemmpEmpTimesheetDeclareDetails = null;

if (mTemmpEmpTimesheetDeclareDetails.Count() > 0)
{
  mEmpTimesheetDeclareDetail = (EmpTimesheetDeclareDetail)mTemmpEmpTimesheetDeclareDetails(0);
}

It gives me error here (EmpTimesheetDeclareDetail)mTemmpEmpTimesheetDeclareDetails(0) Non-invocable member can not be used like a method. Though i understand the error that i am using mTemmpEmpTimesheetDeclareDetails as a method which is incorrect. But how does it accepts it in VB? and how can i achieve this in c#?

Answer 1

You've declared your member as an IEnumerable<T> . An IEnumerable<T> does not support indexing, as it's a sequence of values. You're looking for ElementAt() . So, your code would become:

mEmpTimesheetDeclareDetail = mTemmpEmpTimesheetDeclareDetails.ElementAt(0);

Note that you don't need to cast the result, as the result of ElementOf() will be the same as T (in this case, since you're written IEnumerable<EmpTimesheetDeclareDetail> , the result will be EmpTimesheetDeclareDetail ).

In addition, there's a few other things you can tidy up:

Use .Any() instead of Count() > 0 . Depending on where your sequence comes from, this can prevent the entire sequence from being materialised, it'll only materialise the first item to check if the sequence is not empty.

Also, there exists First and FirstOrDefault() which are a bit clearer than ElementAt(0) . The former will throw an exception if there are no elements, the latter will return null in your case. However, since you've already checked there are elements, First() is more suitable here.

Answer 2

mTemmpEmpTimesheetDeclareDetails(0) should be mTemmpEmpTimesheetDeclareDetails.ElementAt(0)

In c# index should be accessed through a pair of square brackets [] . here Brackets are for calling methods. So when you use mTemmpEmpTimesheetDeclareDetails(0) , the compiler assumes that you are calling a method named mTemmpEmpTimesheetDeclareDetails with an integer parameter.

But in your case you are accessing an IEnumerable<T> based on its index, so you have to use the method .ElementAt(index) , Because Enumerable is more generic, and a collection represented by enumerable may not have an indexer