ASP.NET

One of the developers in our team recently encountered a problem of getting the display name of the current user.
The .NET framework exposes the user name through Environment.UserName or System.Security.Principal.WindowsIdentity.GetCurrent().Name but there’s no API to get the user’s display name.
The simplest implementation to get the display name would be using DirectoryServices:

public static string GetUserFullName(string domain, string userName) { DirectoryEntry userEntry = new DirectoryEntry("WinNT://" + domain + "/" + userName + ",User"); return (string)userEntry.Properties["fullname"].Value; }

The above method can be called with the current user name and domain to get the user’s fullname:

GetUserFullName(Environment.UserDomainName, Environment.UserName)

This method will fail to provide a correct result of the fullname property is not configured in ActiveDirectory.
Windows provide an unmanaged API called GetUserNameEx that can be called using interop:

///

/// Wraps the GetUserNameEx API in secur32.dll
///

///
/// http://msdn2.microsoft.com/en-us/library/ms724435.aspx

///
public static class GetUserNameExUtil
{
#region Interop Definitions public enum EXTENDED_NAME_FORMAT
{ NameUnknown = 0, NameFullyQualifiedDN = 1, NameSamCompatible = 2, NameDisplay = 3, NameUniqueId = 6, NameCanonical = 7, NameUserPrincipal = 8, NameCanonicalEx = 9, NameServicePrincipal = 10, NameDnsDomain = 12,
}
[System.Runtime.InteropServices.DllImport("secur32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto)]

public static extern int GetUserNameEx(int nameFormat, StringBuilder userName, ref int userNameSize);
#endregion public static string GetUserName(EXTENDED_NAME_FORMAT nameFormat)

{
if (Environment.OSVersion.Platform != PlatformID.Win32NT)
{ return null; }
StringBuilder userName = new StringBuilder(1024);
int userNameSize = userName.Capacity;
if (GetUserNameEx((int)nameFormat, userName, ref userNameSize) != 0) { string[] nameParts = userName.ToString().Split('\\');
return nameParts[0];
} return null;
} public static string GetUserFullName()
{ return GetUserName(EXTENDED_NAME_FORMAT.NameDisplay); }
}

Just call GetUserNameExUtil.GetUserDisplayName() to get the user’s display name…