C# – Getting the full file path when using a file upload control

There is actually a (subtle) difference between the two. Imagine you have the following code in File1.cs:

// File1.cs
using System;
namespace Outer.Inner
{
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now imagine that someone adds another file (File2.cs) to the project that looks like this:

// File2.cs
namespace Outer
{
    class Math
    {
    }
}

The compiler searches Outer before looking at those using directives outside the namespace, so it finds Outer.Math instead of System.Math. Unfortunately (or perhaps fortunately?), Outer.Math has no PI member, so File1 is now broken.

This changes if you put the using inside your namespace declaration, as follows:

// File1b.cs
namespace Outer.Inner
{
    using System;
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now the compiler searches System before searching Outer, finds System.Math, and all is well.

Some would argue that Math might be a bad name for a user-defined class, since there's already one in System; the point here is just that there is a difference, and it affects the maintainability of your code.

It's also interesting to note what happens if Foo is in namespace Outer, rather than Outer.Inner. In that case, adding Outer.Math in File2 breaks File1 regardless of where the using goes. This implies that the compiler searches the innermost enclosing namespace before it looks at any using directive.

It's currently true that "when you upload a file the browser will only send the source filename and not the full path" - it makes perfect sense that the server has no business knowing whether the file was in "C:\WINDOWS\" or "F:\SOMEDIR\OTHERDIR\PERSONALINFO\". The filename is always sent, and is useful both to help the user 'recognise' the content and possibly to interrogate the file extension to help determine the file type.

However I know from experience that Internet Explorer definitely used to (in older versions) send the entire path. It's difficult to find an authoritative confirmation (except this apache fileupload control doco)

Internet Explorer provides the entire path to the uploaded file and not just the base file name

Regardless, you should not use nor expect the full path to be sent by any 'modern' browser.