Why remove unused using directives in C#?

c# .net using
bounav picture bounav · Mar 10, 2009 · Viewed 27.3k times · Source

I'm wondering if there are any reasons (apart from tidying up source code) why developers use the "Remove Unused Usings" feature in Visual Studio 2008?

Answer

John Feminella picture John Feminella · Mar 10, 2009

There are a few reasons you'd want to take them out.

  • It's pointless. They add no value.
  • It's confusing. What is being used from that namespace?
  • If you don't, then you'll gradually accumulate pointless using statements as your code changes over time.
  • Static analysis is slower.
  • Code compilation is slower.

On the other hand, there aren't many reasons to leave them in. I suppose you save yourself the effort of having to delete them. But if you're that lazy, you've got bigger problems!

Related questions

What is the C# Using block and why should I use it?

What is the purpose of the Using block in C#? How is it different from a local variable?

Read More
Nested using statements in C#

I am working on a project. I have to compare the contents of two files and see if they match each other precisely. Before a lot of error-checking and validation, my first draft is: DirectoryInfo di = new DirectoryInfo(Environment.CurrentDirectory + "\\…

Read More
When should I use "using" blocks in C#?

Are there particular instances where I should (or shouldn't?) be using "using" blocks: using(SomeType t = new SomeType()){ ... }

Read More