Finding my main executable's path using Assembly vs AppDomain

Question

I'm a .NET user, and my goal is as simple as finding the absolute path of the directory of my main executing assembly (the EXE file).

I have several candidates:

• Assembly.GetExecutingAssembly().CodeBase
• Assembly.GetExecutingAssembly().Location
• AppDomain.CurrentDomain.BaseDirectory

If to judge by the .NET documentation - I'm leaning towards CodeBase. Can anyone shed light over all three in a bit more specific terms than the .NET documentation? An example to demonstrate the difference perhaps?

Answer 1

I would use GetEntryAssembly() instead of GetExecutingAssembly().

To see why, do this:

• Create a new Console Project
• Add a class library project (ClassLibrary1) to the solution and reference it from the Console Project.

Put this in ClassLibrary1:

namespace ClassLibrary1
{
    using System;
    using System.IO;
    using System.Reflection;

    public class Class1
    {
        public void GetInfo(int n)
        {
            Assembly asm = Assembly.GetEntryAssembly();
            Console.WriteLine("[GetEntryAssembly {0}] Location:{1}", n, Path.GetDirectoryName(asm.Location));
            asm = Assembly.GetExecutingAssembly();
            Console.WriteLine("[GetExecutingAssembly() {0}] Location:{1}", n, Path.GetDirectoryName(asm.Location));
        }
    }
}

Put this in console's Program.cs:

namespace ConsoleApplication4
{
    using System;
    using System.IO;
    using System.Reflection;
    using ClassLibrary1;

    class Program
    {
        static void Main(string[] args)
        {
            Assembly asm = Assembly.GetEntryAssembly();
            Console.WriteLine("[GetEntryAssembly() 1] Location:{0}", Path.GetDirectoryName(asm.Location));
            asm = Assembly.GetExecutingAssembly();
            Console.WriteLine("[GetExecutingAssembly() 1] Location:{0}", Path.GetDirectoryName(asm.Location));

            Class1 obj1 = new Class1();
            obj1.GetInfo(2);

            asm = Assembly.LoadFile(@"C:\temp\ClassLibrary1.dll");
            Type t = asm.GetType("ClassLibrary1.Class1");
            object obj2 = asm.CreateInstance("ClassLibrary1.Class1");
            t.GetMethod("GetInfo").Invoke(obj2, new object[] { 3 });

            Console.ReadKey();
        }
    }
}

Build the solution, copy ClassLibrary1.dll to c:\temp and run.

As you will see, GetExecutingAssembly() may trick you in certain conditions.

One last note, if your app is a Windows Forms one, you can just use Application.ExecutablePath.

Answer 2

I'm not sure about AppDomain.CurrentDomain.BaseDirectory, but the difference between Assembly.GetExecutingAssembly().CodeBase and Assembly.GetExecutingAssembly().Location was explained in this blog post.

The CodeBase is a URL to the place where the file was found, while the Location is the path from where it was actually loaded. For example, if the assembly was downloaded from the internet, its CodeBase may start with "http://", but its Location may start with "C:\". If the file was shadow copied, the Location would be the path to the copy of the file in the shadow-copy dir.

It’s also good to know that the CodeBase is not guaranteed to be set for assemblies in the GAC. Location will always be set for assemblies loaded from disk, however.

So it seems your best bet is Location if you need the real directory the file was executed from.

Answer 3

Unfortunately, all the methods above can fail if you use a virtualization like XenoCode postbuild. I have tested many methods and found another solution here. I've found that only the

System.Diagnostics.Process.GetCurrentProcess().ProcessName + ".exe"

returns the correct filename of the executable. So combining the filename with the path from Assembly.GetEntryAssembly().Location you will get the correct path of the executable.