<p>I have been running <a href="http://en.wikipedia.org/wiki/StyleCop" rel="noreferrer">StyleCop</a> over some C# code, and it keeps reporting that my <code>using</code> directives should be inside the namespace.</p>

<p>Is there a technical reason for putting the <code>using</code> directives inside instead of outside the namespace?</p>

Putting it inside the namespaces makes the declarations local to that namespace for the file (in case you have multiple namespaces in the file) but if you only have one namespace per file then it doesn't make much of a difference whether they go outside or inside the namespace.
```
```
using ThisNamespace.IsImported.InAllNamespaces.Here;

namespace Namespace1
{ 
   using ThisNamespace.IsImported.InNamespace1.AndNamespace2;

   namespace Namespace2
   { 
      using ThisNamespace.IsImported.InJustNamespace2;
   }       
}

namespace Namespace3
{ 
   using ThisNamespace.IsImported.InJustNamespace3;
}
```
```