The Windows API
What is the Windows API?
If you look at the Windows System directory, typically \Windows\System under Window 95/98 and \Winnt\System32 under Windows NT and XP, you will find a number of Dynamic Link Library (.DLL) files. These files contain methods that are used to run the operating system and to ensure a consistent user interface and operating environment. These files make up the Windows API.The purpose of the Windows API is to allow you to develop programs consistent with the Windows operating system and user interface. Instead of individuals writing the code to create components of the Windows operating system, such as forms, command buttons, and menus, you can call the appropriate methods in the Windows API and let the operating system create those components.
The purpose of each method in the Windows API is documented in the Platform Software Development Kit (SDK). The Platform SDK is shipped with Microsoft Visual C++ and as part of a subscription to the Microsoft Developer Network (MSDN.)
As with any other Windows program, Visual Basic uses the methods in the Windows API. When you perform a task in Visual Basic, such as adding a command button to a form, Visual Basic calls the appropriate methods to perform the task. The features of Visual Basic are wrappers to these methods
Why Use the Windows API?
The reason why you would use the Windows API is to perform a task beyond what is available from Visual Basic. For example, you cannot determine or set the cursor blinking rate through any statement, property, procedure, or method in Visual Basic. You can get the blink rate by calling the GetCaretBlinkTime method, which returns the cursor blink rate in milliseconds. If you want to set the cursor to blink at another rate under specified conditions, you can call the SetCaretBlinkTime method, passing the specified time in milliseconds.You can get the same methodality as almost any of the features of Visual Basic by calling the appropriate Windows API methods. However, calling these methods directly is typically more complicated and can cause unpredictable behavior and, if not done correctly, resulting in system errors. For the best performance and predictable behavior, you should use the intrinsic Visual Basic methodality.
How to Call a Windows API method
There are two steps required to call a Windows API method: