Introduction to Windows API

last modified July 16, 2020

This is Windows API tutorial. This tutorial will teach you the basics and more advanced topics of programming in Windows API with the C programming language. It does not cover MFC. (Microsoft Foundation Classes is a widely used C++ library for developing C++ applications on Windows.) This tutorial has been created and tested on Windows 7. The examples have been built using Pelles C compiler. If you plan to read this tutorial, you are advised to download and install this compiler. (It is a freeware.) If you want to use some other compiler make sure that is supports the C99 standard.

Windows API

The Windows API is the application programming interface that is used to create Windows applications. In order to create Windows applications, we must download the Windows SDK. (Formerly known as Platform SDK.) The SDK (Software Development Kit) contains header files, libraries, samples, documentation and tools that use the Windows API to develop applications. The Windows API is created for C and C++ programming languages. It is the most direct way to create Windows applications. (If we install Pelles C, the Windows SDK is already included.)

The Windows API can be divided into several areas:

The Base services provide access to the fundamental resources on Windows. These include file systems, devices, processes, threads, registry or error handling. The Security area provides functions, interfaces, objects and other programming elements for authentication, authorisation, cryptography and other security related tasks. The Graphics subsystem provides functionality for outputting graphical content to monitors, printers and other output devices. The User interface provides functionality to create windows and controls. The Multimedia component provides tools for working with video, sound and input devices. The functions of the Windows shell interface allow applications to access the functionality provided by the operating system shell. The Network services provide access to the network capabilities of the Windows OS.

Windows API is an abstract specification of the programming interface to the Windows operating system. It consists of declarations of functions, unions, structures, data types, macros, constants and other programming elements. Windows API is described mainly by the MSDN (Microsoft Developer Network) and resides in the Windows C headers. The official implementation of the Windows API functions is located in dynamic libraries (DLLs). For example kernel32.dll, user32.dll, gdi32.dll, or shell32.dll in the Windows system directory. There are third-party implementations of Windows API: most notably the Wine project and the ReactOS project.

Windows API is a dynamic entity. The number of functions continuously grows with every new version of Windows OS and new service packs. There are also some important differences between the server versions and desktop versions of the operating system. Some functions are not officially documented.

Pelles C

Pelles C is an excellent C compiler and integrated development environment (IDE) for the C programming language. It supports both 32-bit Windows (x86) and 64-bit Windows (x64). It implements both C99 and C11 standards. Pelles C has an integrated resource editor, bitmap, icon and cursor editor, and a hex-dump editor. It is developed by a Swedish developer Pelle Orinius. It comes with Windows SDK, so we can immediately start creating Windows applications without further installations.

Pelles C is a freeware. We can download Pelles C from the following link: Pelles C download.

No target architecture error

In order to create Windows API programs, we have to enable Microsoft extensions. They are not enabled by default; therefore, the compiler produces the following error message: fatal error #1014: #error: "No target architecture". To enable Microsoft extensions, we go to the project options and select the Compiler tab. In this tab we check the Enable Microsoft Extensions box.


The MSDN (Microsoft Developer Network) is a central portal for Windows development. It is a huge collection of material related to development of Windows applications using Microsoft tools. (Third party software like Qt4 or Java Swing is not covered.) It is the most complete reference for the Windows API. The following two links are good entry points for the Windows API reference: the Desktop App Development Documentation and the Windows API list.

This chapter was an introduction to Windows API.