The role of DLLs in Windows systems explained in detail

what is. DLL file.

A DLL is a library that contains code and data that can be used by multiple programs at the same time. For example, in the Windows operating system, the COMDLG32 DLL performs common functions related to dialog boxes. Therefore, each program can use the functionality contained in the DLL to implement the Open dialog box. This helps facilitate code reuse and efficient use of memory.

By using DLLs, programs can be modular and consist of relatively independent components. For example, an accounting program can be sold by module. Each module can be loaded into the main program at run time (if the appropriate module is installed). Because the modules are independent of each other, the program loads faster and the modules are loaded only when the corresponding function is requested.

In addition, updates can be more easily applied to individual modules without affecting other parts of the program. For example, you might have a payroll calculation program, and the tax rate changes every year. When these changes are quarantined in the DLL, you can apply the update without rebuilding or installing the entire program.

The following table describes some of the files that are implemented as DLLs in the Windows operating system:

* ActiveX control (. ocx) file
An example of an ActiveX control is a calendar control that allows you to select a date from a calendar.
* Control Panel (. cpl) file
An example of a. cpl file is an item that is located in Control Panel. Each item is a private DLL.
* Device driver (. drv) file
An example of a device driver is to control the printer driver that prints to the printer.