.DLL File Extension
File Type 1Dynamic Link Library
| Developer | Microsoft |
| Popularity |
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| Category | System Files |
| Format | Binary
BinaryThis file is saved in a binary format, which requires a specific program to read its contents. |
What is a DLL file?
A DLL file is a compiled library that contains a set of procedures and/or drivers that are referenced and executed by a Windows program. It allows multiple programs to access shared functions through common libraries. DLL files are "dynamically linked" into a program at runtime, meaning they are only loaded when needed.
Many DLL files are provided with the Windows operating system, while others are included with Windows programs. They allow various program functions, such as communication with external devices and reading and writing files. In some cases, DLLs are referenced by cross-platform applications running on macOS.
Deleting or modifying the contents of a DLL file may cause errors within the program that references the file. For this reason, DLL files generally should not be opened or edited. However, if an application tries to access a DLL file that has been corrupted or is missing, that program will no longer work. If this happens, you may need to reinstall the program or download and install a new version of the DLL.
mfc42u.dll - A Microsoft Foundation Class (MFC) library required by some Windows programs to run. This DLL is included with Windows XP, Windows Vista, and Windows 7 and is most often located in the C:\Windows\System32\ directory. If you try to open a program and Windows reports that you're missing mfc42u.dll, likely your Windows installation has been damaged. You can use a system restore point or your factory system repair disc to fix the issue. Other related files include mfc42u.dll, mfc40.dll, and mfc40u.dll.
mfc80u.dll - An MFC library required by some Windows programs created with Visual C++ 2005. If you're missing this file, you can install the Microsoft Visual C++ 2005 Redistributable Package to install it. Programs that use this DLL generally install it because it is not included with Windows by default. Other DLLs installed with the package include msvcr80.dll, msvcm80.dll, msvcp80.dll, mfc80.dll, mfcmifc80.dll, and mfcm80.dll.
mfc90u.dll - An MFC library required by some Windows programs created with Visual C++ 2008. If you're missing this file, you can install the Microsoft Visual C++ 2008 Redistributable Package to install it. Programs that use this DLL generally install it because it is not included with Windows by default. Other DLLs installed with the package include msvcr90.dll, msvcm90.dll, msvcp90.dll, mfc90.dll, mfcmifc90.dll, and mfcm90.dll.
mfc100u.dll - An MFC library required by some Windows programs created with Visual C++ 2010. If you're missing this file, you can install the Microsoft Visual C++ 2010 Redistributable Package to install it. Programs that use this DLL generally install it because it is not included with Windows by default. Other DLLs installed with the package include msvcr100.dll, msvcm100.dll, msvcp100.dll, mfc100.dll, mfcmifc100.dll, and mfcm100.dll.
| Windows |
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File Type 2DLL Dynamic Web Page
| Developer | N/A |
| Popularity |
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| Category | Web Files |
| Format | N/A
UnknownFile format categories include Binary, Text, XML, and Zip. The format of this file type has not been determined. |
.DLL File Association 2
Web page generated dynamically when accessed by a user; may incorporate server-side scripts, such as Perl or VB scripts that generate the HTML for the Web page.
Web pages with DLL file extensions are typically hosted on Microsoft IIS Web servers. The DLL extension must be mapped to the correct scripting engine on the server in order for the page to be processed correctly.