C# Signature:

[DllImport("kernel32.dll", SetLastError=true)]
public static extern IntPtr CreateFile(
    string lpFileName,
    EFileAccess dwDesiredAccess,
    EFileShare dwShareMode,
    IntPtr lpSecurityAttributes,
    ECreationDisposition dwCreationDisposition,
    EFileAttributes dwFlagsAndAttributes,
    IntPtr hTemplateFile);

User-Defined Types:

[Flags]
public enum EFileAccess : uint
{
    GenericRead = 0x80000000,
    GenericWrite = 0x40000000,
    GenericExecute = 0x20000000,
    GenericAll = 0x10000000,
}

[Flags]
public enum EFileShare : uint
{
    None = 0x00000000,
    Read = 0x00000001,
    Write = 0x00000002,
    Delete = 0x00000004,
}

public enum ECreationDisposition : uint
{
    New = 1,
    CreateAlways = 2,
    OpenExisting = 3,
    OpenAlways = 4,
    TruncateExisting = 5,
}

[Flags]
public enum EFileAttributes : uint
{
    Readonly = 0x00000001,
    Hidden = 0x00000002,
    System = 0x00000004,
    Directory = 0x00000010,
    Archive = 0x00000020,
    Device = 0x00000040,
    Normal = 0x00000080,
    Temporary = 0x00000100,
    SparseFile = 0x00000200,
    ReparsePoint = 0x00000400,
    Compressed = 0x00000800,
    Offline= 0x00001000,
    NotContentIndexed = 0x00002000,
    Encrypted = 0x00004000,
    Write_Through = 0x80000000,
    Overlapped = 0x40000000,
    NoBuffering = 0x20000000,
    RandomAccess = 0x10000000,
    SequentialScan = 0x08000000,
    DeleteOnClose = 0x04000000,
    BackupSemantics = 0x02000000,
    PosixSemantics = 0x01000000,
    OpenReparsePoint = 0x00200000,
    OpenNoRecall = 0x00100000,
    FirstPipeInstance = 0x00080000
}

Notes:

None.

Tips & Tricks:

You can use the IntPtr from Createfile with FileStream. This is usefull for opening devices such as Com1:, Lpt1: and Prn.

Unlike the FileStream ctor, CreateFile also allows you to open or create Windows 2000 sub-streams (e.g. "C:\Temp.dat:SubStream1").

For example:

IntPtr ptr = CreateFile(filename,access, share,0, mode,0, IntPtr.Zero);
/* Is bad handle? INVALID_HANDLE_VALUE */
if (ptr.ToInt32() == -1)
{
    /* ask the framework to marshall the win32 error code to an exception */
    Marshal.ThrowExceptionForHR(Marshal.GetLastWin32Error());
}
else
{
    return new FileStream(ptr,access);
}

Alternative Managed API:

Do you know one? Please contribute it!

Thought I post a sample code to help out anyone else who may need help : )

/// Sample code provided as is.
/// Sample Composed by Wijaya "Wi" T
/// References:
/// http://www.dotnettalk.net/Needed_help_on_printing_from_C_and_printer-6941579-1297-a.html
/// http://www.dotnet247.com/247reference/msgs/16/84730.aspx
/// http://www.groupsrv.com/dotnet/viewtopic.php?t=72572
/// http://www.pinvoke.net/default.aspx/kernel32.CreateFile
///    Usage:  
///        Initialize this class in your main code (see below),
///        and walla you are now printing!
///        
///        e.g.:
///        PrintFactory objPrintFactory = new PrintFactory();
///    Thank you:
///        Thank you all who have been contributing to printing to LPT port.
///        God Bless you! : )
///    Addt'l info:
///        Don't forget to reference:
///            using System.Runtime.InteropServices;
///            using System.IO;
///            
public class PrintFactory
{
   public const short FILE_ATTRIBUTE_NORMAL = 0x80;
   public const short INVALID_HANDLE_VALUE = -1;
   public const uint GENERIC_READ = 0x80000000;
   public const uint GENERIC_WRITE = 0x40000000;
   public const uint CREATE_NEW = 1;
   public const uint CREATE_ALWAYS = 2;
   public const uint OPEN_EXISTING = 3;        

   [DllImport("kernel32.dll", SetLastError=true)]
   static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess,
       uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition,
       uint dwFlagsAndAttributes, IntPtr hTemplateFile);

   public PrintFactory()
   {
      IntPtr ptr = CreateFile("LPT1", GENERIC_WRITE, 0,
               IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);

      /* Is bad handle? INVALID_HANDLE_VALUE */
      if (ptr.ToInt32() == -1)
      {
     /* ask the framework to marshall the win32 error code to an exception */
     Marshal.ThrowExceptionForHR(Marshal.GetLastWin32Error());
      }
      else
      {                                    
     String Temp = "This is a test print";
     //This is the cut command on Star TSP 600 Printer
     char[] prnCmdCut = {(char)27, (char)100, (char)51};                
     FileStream lpt = new FileStream(ptr,FileAccess.ReadWrite);
     Byte[] Buff = new Byte[1024];
     //Check to see if your printer support ASCII encoding or Unicode.
     //If unicode is supported, use the following:
     //Buff = System.Text.Encoding.Unicode.GetBytes(Temp);
     Buff = System.Text.Encoding.ASCII.GetBytes(Temp);
     lpt.Write(Buff,0,Buff.Length);                     
     Buff = System.Text.Encoding.ASCII.GetBytes(prnCmdCut);
     lpt.Write(Buff,0,Buff.Length);
     lpt.Close();
       }
    }
}