Windows API

A computer has many parts. Programs need to talk to these parts. They use a special set of rules to do this.

These rules help a program show pictures on a screen. They also help a program use a printer. The rules help a program use a mouse or a keyboard too.

One part of these rules helps with files. It lets a program save or open a file. Other parts help with the internet.

These rules are very important. Most programs on a computer use them. This helps everything work together well.

A computer program needs to talk to the system it runs on. It uses a special set of rules to do this. We call this the Windows API.

Think of the API as a bridge. It lets a program reach the features of the Windows operating system. This includes many different jobs. Base services help with files and devices. Advanced services let a program restart the system or manage user accounts. There is also a part called the GDI. The GDI, or Graphics Device Interface, helps show pictures on a monitor or a printer.

The API also helps with the screen you see. It provides buttons and scrollbars. It also helps the computer feel your mouse or keyboard. Other parts help with the internet and network tools.

Microsoft gives tools to help people build software. This is called the Windows SDK. It includes books and tools for makers. Most programs use these rules. This helps all the software work together on one computer. Even as Windows grows, the API stays mostly the same. This helps old programs still work on new computers.

{ "text": "A computer program needs to talk to the system it runs on. The Windows API, or WinAPI, is the foundation for this talk. It is a set of rules that lets programs use the features of the Microsoft Windows operating system.

Without these rules, a program would not know how to work with the computer. Most programs use shared libraries to reach this API. Each major version has a special name to show how it works. For example, Win32 is the name for the version that runs on 32-bit systems. Microsoft even provides a software development kit, called the Windows SDK, to help people build new software.\n\nThis system works by providing many different services to a program. Base services handle important things like the file system and different devices. These functions live in files like kernel32.dll or KernelBase.dll inside the \Windows\System32 folder.

Other parts are called advanced services. These let a program manage user accounts or restart the whole system. There is also a part called the Graphics Device Interface, or GDI. The GDI helps send pictures to your monitor or your printer. It uses files like gdi32.dll to make this happen.\n\nLearning to use this system has a long history. In the early days of Windows 1.0, even a simple program was very hard to make. A writer named Charles Petzold said the first \"hello world\" program was a bit of a scandal. It was about 150 lines of code long!

That is much longer than most simple programs today. Later, he made it much simpler by using a single command. Over the years, the API has grown from 450 function calls to thousands. Even so, the way it works stays similar so old programs can still run.\n\nThere are many specific parts to the Windows API that help it function. The User Interface part creates the buttons and scrollbars you click on. It uses files like user32.dll or comctl32.dll to manage the screen.

There is also a Common Dialog Box Library for choosing colors or fonts. If a program needs to use the internet, it uses Network Services. These services live in a file called netapi32.dll. Even the Internet Explorer web browser uses these APIs to work. This allows the browser to talk to the rest of the computer.\n\nMany different technologies use the Windows API to get things done. Most software running on Windows relies on these rules to function.

Some tools, like the Microsoft Foundation Class Library, make it easier to use C++ code. Other systems, like the .NET runtime or Java, also use the API. It acts like a middle layer between the program and the computer. This way, different types of software can all work together on one machine. It is the glue that holds many programs and the operating system together.", "media": ["ReactOS Frankenstein Email.png"] }

The Windows API, often called WinAPI, is the foundational application programming interface for the Microsoft Windows operating system. An API acts as a bridge that allows a computer program to access and use the specific features of the system it is running on. Without this interface, a program would not be able to communicate with the computer's hardware or software functions. Most programs access these capabilities through system libraries, which are shared libraries. To help developers, Microsoft provides a software development kit known as the Microsoft Windows SDK. This kit includes the documentation and tools necessary for building software based on the API.

The API provides several distinct categories of services to ensure a computer functions correctly. Base services handle essential tasks like managing the file system, hardware devices, processes, and threads. On 32-bit and 64-bit Windows systems, these functions reside in files named kernel32.dll or KernelBase.dll. These files are located in the \Windows\System32 folder. Advanced services offer more complex control, such as managing user accounts or restarting the system. These functions are found in files like advapi32.dll. By separating these tasks, the operating system can manage different levels of importance and complexity.

Visual elements of a computer are managed through specialized components like the Graphics Device Interface, or GDI. The GDI provides the features needed to output graphics to monitors and printers. On 32-bit Windows, this component resides in gdi32.dll. For deeper system work, kernel-mode GDI support is provided by win32k.sys, which talks directly to the graphics driver. The User Interface component is another vital part of the system. It manages screen windows, buttons, and scrollbars, while also receiving mouse and keyboard input. This part of the API uses files like user32.dll to manage the graphical user interface, or GUI.

To make software look and feel consistent, the API includes several specialized libraries for user interaction. The Common Dialog Box Library, found in comdlg32.dll, provides standard windows for opening files or choosing fonts. The Common Control Library, which uses the file comctl32.dll, provides more advanced tools like progress bars, toolbars, and tabs. There is also the Windows Shell, which allows programs to access the operating system shell through shell32.dll. For internet-related tasks, Network Services provide access to networking abilities through netapi32.dll. Even the Internet Explorer web browser uses these APIs to function within the system.

Programming for the Windows API has a long and interesting history. In the early days of Windows 1.0, the API was much smaller, supporting fewer than 450 function calls. Today, modern versions of the API support thousands of calls. However, the interface has remained fairly consistent so that old applications can still work. A programmer named Charles Petzold noted that the original "hello world" program in the Windows 1.0 SDK was surprisingly complex. It required about 150 lines of code in the C language and 20 lines in a resource script. This was much more work than the simple single-line commands used by programmers today.

One of the most significant changes in the API's history was the transition from Win16 to Win32. Win16 was used for older systems like Windows 3.1, while Win32 was introduced with Windows NT and became widespread with Windows 95. To help developers move from the old system to the new one, Microsoft used a complex scheme called API thunks. These thunks allowed 32-bit code to call into 16-bit code and vice versa. This made the transition much smoother for software creators. Even modern 64-bit Windows versions use tools like WoW64 to run 32-bit applications through the SysWOW64 folder.

Because the Windows API is so central, many other technologies are built on top of it. The API is based on the C programming language, but it can be used by almost any language that can interact with its data structures. Many developers use "middle-ware" to make interaction easier. For example, the Microsoft Foundation Class Library, or MFC, allows developers to use C++ classes to interact with the API in an object-oriented way. Other frameworks like the .NET runtime and the Java virtual machine also provide access to the API. This makes the Windows API the essential link that connects diverse software to the power of the Windows operating system.