File Extension DEF

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DEF File Extension Description

The DEF file extension is a format used by programs created via Microsoft Visual C++ and Borland C++ as a definition file for the Dynamic Link Libraries (DLL) utilized in assorted applications.

The .def file format, or module-definition file, is defined as a text file with one or more statements that define the attributes of different modules or libraries, which will then add functionalities to Windows-based programs, usually in the form of DLLs.

Usually, a .def text file is used only when the programmer is not working with the DLL export functions _declspec or _dllexport.

A file with a .def format must contain the following statements to define modules (DLLs):

Initially, the first statements found in a DEF file are the LIBRARY statements, which attribute the file a certain DLL. Right after the LIBRARY statement is coded, the name of the DLL must be stated to complete the code. This will automatically initialize the linker to place this name in the imported library of the DLL

EXPORT statements should be included in the DEF file that will list the names and possible ordinal values of each function exported by the module or DLL. The ordinal values can be assigned by simply adding the ?@? symbol at the end of the function name followed by a number.

The sample statement below maps out the content of a DEF file:

LIBRARY BTREE

EXPORTS

Insert @1

Delete @2

Member @3

Min @4

Note that when you specify your own ordinal number to the function name, the minimum value you can assign is 1; the maximum number will depend on the number of function exported by the specified DLL.

• Properties:

• Common Path:
  (user defined)
• Associated Applications:
  Microsoft Visual C++, Borland C++

Additional DEF File Info:

Microsoft Corporation , DEF File Created by: http://www.microsoft.com/

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