How do I get the current username in .NET using C#?

Option A)

string userName = System.Security.Principal.WindowsIdentity.GetCurrent().Name;

• Returns: NetworkName\Username
• Gets the user's Windows logon name.
• Details: https://docs.microsoft.com/en-us/dotnet/api/system.security.principal.windowsidentity

Option B)

string userName = Environment.UserName

• Returns: Username
• Gets the user name of the person who is associated with the current thread.
• Details: https://docs.microsoft.com/en-us/dotnet/api/system.environment.username

Try the property: Environment.UserName.

Use:

System.Security.Principal.WindowsIdentity.GetCurrent().Name

That will be the logon name.

Just in case someone is looking for user Display Name as opposed to User Name, like me.

Here's the treat :

System.DirectoryServices.AccountManagement.UserPrincipal.Current.DisplayName

Add Reference to System.DirectoryServices.AccountManagement in your project.

String myUserName = Environment.UserName

This will give you output - your_user_name

You may also want to try using:

Environment.UserName;

Like this...:

string j = "Your WindowsXP Account Name is: " + Environment.UserName;

Hope this has been helpful.

try this

ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT UserName FROM Win32_ComputerSystem");
ManagementObjectCollection collection = searcher.Get();
string username = (string)collection.Cast<ManagementBaseObject>().First()["UserName"];

now it looks better

In case it's helpful to others, when I upgraded an app from c#.net 3.5 app to Visual Studio 2017 this line of code User.Identity.Name.Substring(4); threw this error "startIndex cannot be larger than length of string" (it didn't baulk before).

It was happy when I changed it to System.Security.Principal.WindowsIdentity.GetCurrent().Name however I ended up using Environment.UserName; to get the logged in Windows user and without the domain portion.

I went over most of the answers here and none of them gave me the right user name.

In my case I wanted to get the logged in user name, while running my app from a different user, like when shift+right click on a file and "Run as a different user".

The answers I tried gave me the 'other' username.

This blog post supplies a way to get the logged in user name, which works even in my scenario:
https://smbadiwe.github.io/post/track-activities-windows-service/

It uses Wtsapi

Edit: the essential code from the blog post, in case it ever disappears, is

Add this code to a class inheriting from ServiceBase

[DllImport("Wtsapi32.dll")]
private static extern bool WTSQuerySessionInformation(IntPtr hServer, int sessionId, WtsInfoClass wtsInfoClass, out IntPtr ppBuffer, out int pBytesReturned);
[DllImport("Wtsapi32.dll")]
private static extern void WTSFreeMemory(IntPtr pointer);
 
private enum WtsInfoClass
{
    WTSUserName = 5, 
    WTSDomainName = 7,
}
 
private static string GetUsername(int sessionId, bool prependDomain = true)
{
    IntPtr buffer;
    int strLen;
    string username = "SYSTEM";
    if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WtsInfoClass.WTSUserName, out buffer, out strLen) && strLen > 1)
    {
        username = Marshal.PtrToStringAnsi(buffer);
        WTSFreeMemory(buffer);
        if (prependDomain)
        {
            if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WtsInfoClass.WTSDomainName, out buffer, out strLen) && strLen > 1)
            {
                username = Marshal.PtrToStringAnsi(buffer) + "\\" + username;
                WTSFreeMemory(buffer);
            }
        }
    }
    return username;
}

If you don't have one already, add a constructor to the class; and add this line to it:

CanHandleSessionChangeEvent = true;

EDIT: Per comments requests, here's how I get the session ID - which is the active console session ID:

[DllImport("kernel32.dll")]
private static extern uint WTSGetActiveConsoleSessionId();

var activeSessionId = WTSGetActiveConsoleSessionId();
if (activeSessionId == INVALID_SESSION_ID) //failed
{
    logger.WriteLog("No session attached to console!");    
}