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Does Your App Know Where it's Running

By , 2 Feb 2011
 
Have you ever wondered how to determine if your application is running as a standalone app or from within the Visual Studio IDE? I needed to do that today, and it took some scrounging around, but this is what I came up with.
 
If you go look in your (compiled) project's bin\debug (or bin\release) folder, you'll probably find a file named something like this:
 
MyApplication.vshost.exe
 
That application is an execution proxy used by Visual Studio to run your actual application. It provides three primary benefits to your development efforts:
 
It provides the following benefits:
 
* It improves performance by creating the AppDomain and initializing the debugger.
 
* It simulates a partial trust environment inside the IDE
 
* It allows design-time expression evaluation and supports the Immediate window.
 
Now that we know what it does (not that it really matters), let's exploit it. Essentially, you need to do two things to make this tip work:
 
0) Calling Application.ExecutablePath returns the full path to your actual application, i.e. C:\dev\MySolution\MyProj\bin\debug\MyApp.exe
 
1) If you use InteropServices to call GetModuleFileName, the returned path is C:\dev\MySolution\MyProj\bin\debug\MyApp.vshost.exe.
 
If the two names do NOT match, you're app is running in the IDE (even if the debugger isn't attached).
 
Ain't life a peach sometimes? Here's the whole code snippet.
 
using System.Windows.Forms;
using System.InteropServices;
 
public static class Globals
{
    [DllImport("kernel32.dll", SetLastError=true)]
    private static extern int GetModuleFileName([In]IntPtr hModule, 
                                                [Out]StringBuilder lpFilename, 
                                                [In][MarshalAs(UnmanagedType.U4)] int nSize);
 
    //--------------------------------------------------------------------------------
    public static bool RunningInVisualStudio()
    {
        StringBuilder moduleName = new StringBuilder(1024);
        int result = GetModuleFileName(IntPtr.Zero, moduleName, moduleName.Capacity);
        string appName = Application.ExecutablePath.ToLower();
        return (appName != moduleName.ToString().ToLower());
    }
}
 
One caveat exists - This technique can be rendered useless by going to the project's Properties page, clicking on the Debug tab, and then unchecking the check box that reads "Enable the Visual Studio Hosting Process". My advice - don't uncheck that box.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

John Simmons / outlaw programmer
Software Developer (Senior)
United States United States
Member
I've been paid as a programmer since 1982 with experience in Pascal, and C++ (both self-taught), and began writing Windows programs in 1991 using Visual C++ and MFC. In the 2nd half of 2007, I started writing C# Windows Forms and ASP.Net applications, and have since done WPF, Silverlight, WCF, web services, and Windows services.
 
My weakest point is that my moments of clarity are too brief to hold a meaningful conversation that requires more than 30 seconds to complete. Thankfully, grunts of agreement are all that is required to conduct most discussions without committing to any particular belief system.

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GeneralReason for my vote of 5 Good researchmemberPranit Kothari6 Nov '11 - 20:42 
Reason for my vote of 5
Good research
GeneralReason for my vote of 5 Great! I've need something like that...subeditorWalt Fair, Jr.15 Aug '11 - 15:20 
Reason for my vote of 5
Great! I've need something like that a few times.
GeneralI feel like there's a joke somewhere in this title.. :D Good...memberAndrew Rissing3 Feb '11 - 3:53 
I feel like there's a joke somewhere in this title.. Big Grin | :-D Good stuff.
GeneralReason for my vote of 5 Thanks for sharingmemberlinuxjr2 Feb '11 - 12:10 
Reason for my vote of 5
Thanks for sharing
GeneralYou can also use Process.GetCurrentProcess().MainModule.File...memberTiefeng You2 Feb '11 - 11:45 
You can also use Process.GetCurrentProcess().MainModule.FileName to get moduleName instead of interop
GeneralRe: that's nicer, no interop necessary using System.Diagnostics;...memberwknopf7 Feb '11 - 6:51 
that's nicer, no interop necessary
using System.Diagnostics;
 
public static bool RunningInVisualStudio()
{
string appName = Process.GetCurrentProcess().MainModule.FileName.ToString();
return (appName.Contains(".vshost."));
}
 

GeneralReason for my vote of 5 Cool. Much better than my workaroun...memberPSU Steve2 Feb '11 - 2:53 
Reason for my vote of 5
Cool. Much better than my workaround of putting a flag-file in the BIN directory. Thanks!
GeneralReason for my vote of 5 nice onememberPranay Rana1 Feb '11 - 23:59 
Reason for my vote of 5
nice one
Generalgood one..memberMember 19908561 Feb '11 - 22:50 
good one..
GeneralIts great work and a very good research. I was unaware of it...memberUmair Feroze1 Feb '11 - 22:22 
Its great work and a very good research. I was unaware of it. Thanks John
Generalwhy did you need to know if you're running under the IDE pro...membercechode1 Feb '11 - 18:40 
why did you need to know if you're running under the IDE process or not. ( as apposed to weather or not you are debugging or not? )
 
if you don't mind me asking.
GeneralRe: Because I wanted some code to run differently if the app was...mvpJohn Simmons / outlaw programmer1 Feb '11 - 23:50 
Because I wanted some code to run differently if the app was running in the IDE.
GeneralRe: why did you need to know if you're running under the IDE pro...memberfastal31 May '12 - 4:18 
Any time you have an app that takes command line arguments, well, you can put them in the project, but sometimes it's handier to make the program ask for them (or handier to hardcode them or have the program auto-deduce them) especially if they are long or change frequently. This is to increase testing productivity. If you never had to do that this would seem stupid. But if you are manually testing 100 times (really not verify much except for trivial apps) and it takes you 30sec longer to update project properties than to enter a GUI or have the program figure them out, you're losing an hour, so if it takes 10 minues for the gui, that's 40 minutes of youtube time you've gained.
GeneralBut...memberPIEBALDconsult13 Dec '11 - 8:35 
I disable the VSHost -- I have no use for it, didn't need it with VS.net 2002, don't need it now. Big Grin | :-D
GeneralRe: But...memberfastal31 May '12 - 4:15 
If you disable it, you lose edit-and-continue. That has saved me 100s of hours, not only recompiling, but not having to re-load/enter the case into the LOB apps I work on, I can re-test and just fly on. Wonderful productivity enhancer.

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