What is the correct way use of "using" in C#.NET?

Question

which approaches are correct about "using" (first or second)?

First:

using (DataTable dt = list.ToDataTable())
{
     dataList.DataSource = dt;
     dataList.DataBind();
}

Second:

 using (DataTable dt = list.ToDataTable())
 {
     dataList.DataSource = dt;
 }
 dataList.DataBind();

`DataTable` does not implement `IDisposable`, so you can't use it within `using` statement... — MarcinJuraszek, Aug 21 '13 at 10:11
@MarcinJuraszek - really? I must be imagining the `Dispose()` and `Dispose(bool)` [methods](http://msdn.microsoft.com/en-us/library/system.data.datatable.aspx) that it inherits from `MarshalByValueComponent`. — Damien_The_Unbeliever, Aug 21 '13 at 10:14
Ah a DataTable IS disposable, but it SHOULD NOT be used. This was a recommendation from Microsoft, calling the Disposabillity a mistake. — Christian Sauer, Aug 21 '13 at 10:14
@Damien_The_Unbeliever wow, you got me! I only checked `DataTable` class signature... — MarcinJuraszek, Aug 21 '13 at 10:15
Did you try out these two approaches yourself? The second should not actually work because you are using DataBind after the object has been disposed. — Amicable, Aug 21 '13 at 10:21
In second approach you are gonna call DataBind() on disposed object. — Agares, Aug 21 '13 at 10:12

score 3 · Accepted Answer · answered Aug 21 '13 at 10:13

Well in your case it has to be the first approach otherwise you will dispose of the DataTable before it's been used (so DataBind() in the second would throw an exception).

In general though, you only need to keep code which uses the disposable object within the scope of the using.

What is the correct way use of "using" in C#.NET?

1 Answers1