Error LNK1169 one or more multiply defined symbols found

When I compile the demo from pretty WinAPI class.

Error LNK1169 one or more multiply defined symbols found

1. HOW TO FIX IT? SOS! fatal error LNK1169: one or more multiply defined symbols found

## This error is preceded by error LNK2005. Generally, this error means you have broken the one definition rule, which allows only one definition for any used template, function, type, or object in a given object file, and only one definition across the entire executable for externally visible objects or functions.

Do you meet this error when you are running test project? And does your project build/debug well without any error?

According to the official document, You could refer to below possible causes and for solutions please refer to this link Possible causes and solutions.

1. (1) Check if one of your header file defines a variable and maybe include this header file in more than one source file in your project.
2. (2) This error can occur when a header file defines a function that isn’t inline. If you include this header file in more than one source file, you get multiple definitions of the function in the executable.
(3) This error can also occur if you define member functions outside the class declaration in a header file. (4) This error can occur if you link more than one version of the standard library or CRT. (5) This error can occur if you mix use of static and dynamic libraries when you use the /clr option (6) This error can occur if the symbol is a packaged function (created by compiling with /Gy) and it was included in more than one file, but was changed between compilations. (7) This error can occur if the symbol is defined differently in two member objects in different libraries, and both member objects are used. One way to fix this issue when the libraries are statically linked is to use the member object from only one library, and include that library first on the linker command line. (8) This error can occur if an extern const variable is defined twice, and has a different value in each definition.
3. (9) This error can occur if you use uuid.lib in combination with other .lib files that define GUIDs (for example, oledb.lib and adsiid.lib).

There are some similar issues and maybe helpful.

• LNK1169 and LNK2005 Errors.
• Fatal error LNK1169: one or more multiply defined symbols found in game programming.
• Fatal error LNK1169: one or more multiply defined symbols found..
2. fatal error LNK1169: one or more multiply defined symbols found in game programming

However to me, it seems that the entire code is written properly and the two ints are only mentioned in the Global header and all objects seem to be inheriting properly. However, like I just said, I'm a beginner in OOP so I really need an opinion : It is also worth mentioning that I am using allegro 5 to create a side shooter..

3. One or more multiply defined symbols found

But why does this happen? I have #ifndef #define and #endif in the header so multiple definitions shouldn't happen.

4. "multiple defined symbols error" when using stdafx.h with own headers [duplicate]

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5. multiple definition in header file

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6. Damn compiler linker errors: fatal error LNK1169

I was happily programming a small DX game in VC++, when all of a sudden the next time I try to compile it, I get a linker error:

Debug/CreateDevice.exe : fatal error LNK1169: one or more multiply defined symbols found

I looked in MSVC, and found a little info on the error, here it is:

Linker Tools Error LNK2005 symbol already defined in object

The given symbol, displayed in its decorated form, was multiply defined. Tips One of the following may be a cause:

The most common cause of this error is accidentally linking with both the single-threaded and multithreaded libraries. Ensure that the application project file includes only the appropriate libraries and that any third-party libraries have appropriately created single-threaded or multithreaded versions. The given symbol was a packaged function (created by compiling with /Gy) and was included in more than one file but was changed between compilations. Recompile all files that include the symbol. The given symbol was defined differently in two member objects in different libraries, and both member objects were used. An absolute was defined twice, with a different value in each definition. This error is followed by fatal error LNK1169. Linker Tools Error LNK1169 one or more multiply defined symbols found The build failed due to multiple definitions of one or more symbols. This error is preceded by error LNK2005. The /FORCE or /FORCE:MULTIPLE Syntax /FORCE:{MULTIPLE|UNRESOLVED} This option tells the linker to create a valid .EXE file or DLL even if a symbol is referenced but not defined or is multiply defined. On the command line, the /FORCE option can take an optional argument: Use /FORCE:MULTIPLE to create an output file whether or not LINK finds more than one definition for a symbol. Use /FORCE:UNRESOLVED to create an output file whether or not LINK finds an undefined symbol. A file created with this option may not run as expected. The linker will not link incrementally when the /FORCE option is specified. To find this option in the development environment, click Settings on the Project menu. Then click the Link tab, and click Customize in the Category box.

I have been unable to find the cause of the error, and anyway what is a: 1. absolute 2. multiply defined symbol 3. single-threaded and multithreaded libraries please can you help me out? Is their a easy way to find out what the cause is? ect.

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