Using Statements in C#

Question

Good programming habits questions. Do additional using statements that the Class does not use affect the speed of the application?

Example I have a Class called StoreController -

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

However, it only needs

using System.Web.Mvc; //Love some Resharerper

My question still, does it really affect the application to have the unused using statements?

Those are [using directives](http://msdn.microsoft.com/en-us/library/sf0df423.aspx). C# *has* a [using statement](http://msdn.microsoft.com/en-us/library/yh598w02.aspx) but it's something different. It helps, when there are two features that use the same keyword, to use the correct terminology. — Damien_The_Unbeliever, Jan 02 '14 at 15:54
I think it might be helpful. http://stackoverflow.com/questions/12026820/do-unused-usings-in-net-affect-performance — Farhad Jabiyev, Jan 02 '14 at 15:55

score 2 · Accepted Answer · answered Jan 02 '14 at 15:54

2

There's no impact at runtime, however having a bunch of useless text in the screen bothers your fellow developers. Remove unused Usings, always.

Edit: using System.Linq; is to C# as air breathing is to humans. Leave it there always, even if it's not being used at present.

answered Jan 02 '14 at 15:54

Federico Berasategui

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@GrantWinney I have excluded that namespace from R#'s "Removed Unused Usings" feature in my Visual Studio =) – Federico Berasategui Jan 02 '14 at 16:00
1

+1 for System.Linq. Removing it is to be considered heresy. – Yandros Jan 02 '14 at 16:13

score 1 · Answer 2 · answered Jan 02 '14 at 15:54

1

Grant's comment is the correct. The using directives are used during compilation to determine the correct type references. They do not affect application execution.

answered Jan 02 '14 at 15:54

jjrdk

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Using Statements in C#

2 Answers2