Programmatically retrieve Visual Studio install directory

Registry Method

I recommend querying the registry for this information. This gives the actual installation directory without the need for combining paths, and it works for express editions as well. This could be an important distinction depending on what you need to do (e.g. templates get installed to different directories depending on the edition of Visual Studio). The registry locations are as follows (note that Visual Studio is a 32-bit program and will be installed to the 32-bit section of the registry on x64 machines):

• Visual Studio: HKLM\SOFTWARE\Microsoft\Visual Studio\Major.Minor:InstallDir
• Visual C# Express: HKLM\SOFTWARE\Microsoft\VCSExpress\Major.Minor:InstallDir
• Visual Basic Express: HKLM\SOFTWARE\Microsoft\VBExpress\Major.Minor:InstallDir
• Visual C++ Express: HKLM\SOFTWARE\Microsoft\VCExpress\Major.Minor:InstallDir

where Major is the major version number, Minor is the minor version number, and the text after the colon is the name of the registry value. For example, the installation directory of Visual Studio 2008 Professional would be located at the HKLM\SOFTWARE\Microsoft\Visual Studio\9.0 key, in the InstallDir value.

Here's a code example that prints the installation directory of several versions of Visual Studio and Visual C# Express:

string visualStudioRegistryKeyPath = @"SOFTWARE\Microsoft\VisualStudio";
string visualCSharpExpressRegistryKeyPath = @"SOFTWARE\Microsoft\VCSExpress";

List<Version> vsVersions = new List<Version>() { new Version("10.0"), new Version("9.0"), new Version("8.0") };
foreach (var version in vsVersions)
{
    foreach (var isExpress in new bool[] { false, true })
    {
        RegistryKey registryBase32 = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32);
        RegistryKey vsVersionRegistryKey = registryBase32.OpenSubKey(
            string.Format(@"{0}\{1}.{2}", (isExpress) ? visualCSharpExpressRegistryKeyPath : visualStudioRegistryKeyPath, version.Major, version.Minor));
        if (vsVersionRegistryKey == null) { continue; }
        Console.WriteLine(vsVersionRegistryKey.GetValue("InstallDir", string.Empty).ToString());
    }

Environment Variable Method

The non-express editions of Visual Studio also write an environment variable that you could check, but it gives the location of the common tools directory, not the installation directory, so you'll have to do some path combining. The format of the environment variable is VS*COMNTOOLS where * is the major and minor version number. For example, the environment variable for Visual Studio 2010 is VS100COMNTOOLS and contains a value like C:\Program Files\Microsoft Visual Studio 10.0\Common7\Tools.

Here's some example code to print the environment variable for several versions of Visual Studio:

List<Version> vsVersions = new List<Version>() { new Version("10.0"), new Version("9.0"), new Version("8.0") };
foreach (var version in vsVersions)
{
    Console.WriteLine(Path.Combine(Environment.GetEnvironmentVariable(string.Format("VS{0}{1}COMNTOOLS", version.Major, version.Minor)), @"..\IDE"));
}

I use this method to find the installation path of Visual Studio 2010:

    private string GetVisualStudioInstallationPath()
    {
        string installationPath = null;
        if (Environment.Is64BitOperatingSystem)
        {
            installationPath = (string)Registry.GetValue(
               "HKEY_LOCAL_MACHINE\\SOFTWARE\\Wow6432Node\\Microsoft\\VisualStudio\\10.0\\",
                "InstallDir",
                null);
        }
        else
        {
            installationPath = (string)Registry.GetValue(
       "HKEY_LOCAL_MACHINE\\SOFTWARE  \\Microsoft\\VisualStudio\\10.0\\",
              "InstallDir",
              null);
        }
        return installationPath;

    }

I'm sure there's a registry entry as well but I couldn't easily locate it. There is the VS90COMNTOOLS environment variable that you could use as well.

Environment: Thanks to Zeb and Sam for the VS*COMNTOOLS environment variable suggestion. To get to the IDE in PowerShell:

$vs = Join-Path $env:VS90COMNTOOLS '..\IDE\devenv.exe'

---

Registry: Looks like the registry location is HKLM\Software\Microsoft\VisualStudio, with version-specific subkeys for each install. In PowerShell:

$vsRegPath = 'HKLM:\Software\Microsoft\VisualStudio\9.0'
$vs = (Get-ItemProperty $vsRegPath).InstallDir + 'devenv.exe'

[Adapted from here]