Get Windows Login name

We can get the windows login in 2 ways,

1) Using Environment

str = System.Environment.UserDomainName + "\" + System.Environment.UserNamestr;
str will Contain the Login name with the domain name.

2) Using the System.Security

Using System.Security.Principal;
WindowsPrincipal wp = New WindowsPrincipal(WindowsIdentity.GetCurrent());
MessageBox.Show("Your login id:" + wp.Identity.Name);

3) Using SystemInformation

System.Windows.Forms.SystemInformation.UserName;