What is the API file

APIs (application Programming Interface, application programming interfaces) are pre-defined functions designed to provide the ability of applications and developers to access a set of routines based on a piece of software or hardware without having to access the source code. Or understand the details of the internal working mechanism. API In addition to the application of the "application Interface" meaning, but also refers to the API's documentation, also known as the Help document. In addition, it is the American Petroleum Association, Air Pollution Index, medicine, air position indicator in English abbreviation.
WindowsAPI is a set of components to control windows (from the look of the desktop to the memory allocated for a new process) The appearance and behavior of a set of predefined Windows functions. Each action of the user will cause one or several functions to run to tell Windows what is going on. This is somewhat like the natural code of Windows. Other languages simply provide a way to access the API automatically and easily. vb in this respect has made a very More work. It completely hides the API and provides a completely different approach to programming in the Windows environment. This means that every line of code you write with VB is translated by VB into the API function passed to Windows. For example, Form1.print ... VB will call TextOut this API function with some parameters (provided in your code, or default parameters). Similarly, when you click a button on a form, Windows sends a message to the form (which is hidden for you), and VB gets the call and parses it to generate a specific event (Button_Click). The API functions are included in the Dynamic connection library file (such as User32.dll,gdi32.dll,shell32.dll ...) in the Windows system directory. It is easier to understand that Windows is a multi-job system that coordinates application execution, allocates memory, and manages system resources ... , she is also a very large service center, call the service center of the various services (each service is a function), can help the application to open windows, graphics, use peripheral devices ... And so on, since the object of these function services is an application (application), it is called Application programminginterface, or API function. The WIN32 API is the application programming interface of the MicrosoftWindows 32-bit platform. Any application that executes under the Windows operating environment can call the Windows API.

What is the API file