Hello guys today i am going to tell about win32 API or windows programming.so let gets start....
History
Windows was originally a 16- bit graphical layer for MS-DOS that was written by Microsoft. As it grew, it gained the ability to handle 32-bit programs and eventually became totally 32-bit when Windows NT and 2000 came out. After Windows 95, Microsoft began to remove dependencies on DOS and finally fully implemented the separation in Windows 2000. Windows has many advanced features as well as many platform specific problems. It possesses an Application Programming Interface that consists of thousands of mostly undocumented GUI functions as well as having varying degrees of MS-DOS compatibility. Additionally, with the advent of NT (New Technology), Windows relies completely on the NT kernel instead of its MS-DOS subsystem, the NT kernel is capable of emulating the necessary DOS functionality. In addition to the NT kernel, Microsoft has also introduced many API wrappers, suchasthe MFCs (Microsoft Foundation Classes), COM(Component Object Model), and .NET technologies. The most popular languages for use on Windows include Visual Basic/VB61 and C/C++2, although C++is quickly being replaced by the .NET3 platform, specificallyC#4 (CSharp).
Windows Kernels
Windows 1.0, 2.0, and 3.11 are considered to be an older generation of Windows systems that were built to be a simple graphical layer over the MS-DOS operating system. Windows 95, Windows 98, and Windows ME were designed to bypass MS-DOS (although DOS was still present), and were all based on the same code structure known as the "9x Kernel". Windows NT 4.0, Windows 2000, Windows XP, Windows Vista, Windows 7, and Windows Server are all based on a collection of code known as the "NT Kernel".
System Architecture
The Windows NT Kernel is divided into several sections, here we will briefly discuss how the Windows operating system is put together. At the most basic level is the file NTOSKRNL.EXE, the kernel of the Windows operating system, and the most important file on your computer. If you are interested in seeing this for yourself, you can find it in the C:\Windows\System32 folder (this can also be found using the following path %systemroot%\system32 ) on your own Windows NT machines. NTOSKRNL.EXE provides some of the basic functionality of Windows, but one file alone cannot make the whole system work. NTOSKRNL relies heavily on a Dynamic Link Library (DLL) known as HAL.DLL. HAL stands for "Hardware Abstraction Layer", and is the portion of code that allows low-level mechanisms such as interrupts and BIOS communication to be handled independently. If we consider Windows architecture as a layered architecture, with NTOSKRNL.EXE and HAL.DLL on the bottom layer,the next layer up contains two important files,NTDLL.DLL, and WIN32K.SYS. NTDLL contains a number of user-mode functions such as system call stubs and the run-time library (RTL) code, collectively known as the (largely undocumented) "Native API". Much of the run-time library code is shared between NTOSKRNL andNTDLL.WIN32K.SY Sisa kernel-mode driver that implements windowing and graphics, allowing for user interfaces to be created. Thenextlayerupcontainsanumberoflibrariesthatwillbeofprimaryinteresttous. This layer comprises what is called the Win32 API, and it contains (almost) all the functions that a user will need in order to program in Windows. The Win32 API is divided into 4 component parts, each one a .DLL:
kernel32.DLL
This contains most of the system-related Win32 API functions. Most of these functions are just wrappers around the lower-level NTDLL functions, but some functionality such as National Language Support (NLS) and console handling are not available in NTDLL. advapi32.DLL This contains other system-related functions such as registry and service handling. gdi32.DLL This contains a number of basic functions for drawing. These functions are all relatively simple, and allow the user to draw shapes (circles, rectangles, etc.) on the screen, to display and manipulate bitmaps, etc.
user32.DLL
This contains a number of functions that implement the familiar user-interface of Windows. Programs, message boxes, prompts, etc are all implemented using the User32 functions. User32 performs its tasks by calling system calls implemented by WIN32K.SYS. In addition to the 4 primary libraries in the Win32 API, there are a number of other important libraries that a Windows programmer should become familiar with:
MSVCRT.DLL
MSVCRT.DLL is the dynamic link library that contains the implementations of the C standard library (stdlib) functions that C programmers should be familiar with. These are the functions defined in the common header files stdio.h, string.h, stdlib.h, etc.
WS2_32.DLL
This is the Winsock2 library, that contains the standard Berkeley socket API for communicating on the internet.
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