Question

In my application, after the user logs in I set a few picturebox/button/etc images and do some scaling on them and whatnot. I use relative paths for example:

@".\Images\SomeImage.png"

It works fine when the application is launched directly, but if you try to run it via another application:

Process process = new Process();
process.StartInfo.FileName = networkPath;
process.Start();

It dies and comes up with a file not found error, because it cannot locate the images. It also does this if I try to launch it via the command prompt. The executable is stored on a network drive. Why won’t the relative path work in this situation? I can just go ahead and hard code the full path but that makes me feel dirty… Any thoughts?

Answer 1

This is because the working directory is different – by default when starting a new process the working directory for the new process is set to the working directory of the existing process (which will in turn probably be the directory that existing application is contained within).

Normally your application will be run with the working directory as the directory that the executable is contained in – this is the default when creating a new shortcut for example (you can see this in the shortcut properties under the “Start in” field.

When your application is run from the command prompt or from another application however the working directory is changed and the relative paths are resolved to a completely different directory.

You can either change the calling application to se the WorkingDirectory property of the new process to the value it expects, however the proper way of fixing this it to modify your application so that it uses absolute paths based on the path to the executable. Assembly.GetExecutingAssembly().Location can be used to get the path to the executable being run and so the following code should do the trick:

static string GetAbsolutePathFromRelative(string RelativePath)
{
    string directory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
    string absolutePath = Path.Combine(directory, RelativePath);
    // This final call is to stop paths like "C:\Dir\..\OtherDir\file.txt" being returned
    return Path.GetFullPath(absolutePath);
}