CODEWITHSUNDEEP
visual-studio-2013linkerzliblibpng
codetemplar
codetemplar

Reputation: 681

Unresolved external symbol with zlib and libpng. Visual studio 2013

As I need to link to static C runtimes I decided to build all as static librarys in question with the same version of Visual Studio (2013) using the same Platform Toolset and Runtime libraries Multi-Threaded /MT

I am trying to get my application to link to a 3rd party game engine. This engine is built on top of libpng and zlib. libpng is also built on top of zlib.

So I build zlib from scratch into a static library. I then build libpng and point it to the zlib as an additional dependency so zlib gets linked in to my libpng static library.

I then build my game engine linking to both libpng and zlib as additional dependencies. The linker removes the second zlib definition. So far all builds fine.

I then link my application just to my game engine static library. I get linker errors like:

    2>libOxygine-vc120-mt-gd.lib(unzip.obj) : error LNK2001: unresolved external symbol _inflate
    2>libOxygine-vc120-mt-gd.lib(pngrutil.obj) : error LNK2001: unresolved external symbol _inflate
    2>libOxygine-vc120-mt-gd.lib(unzip.obj) : error LNK2001: unresolved external symbol _inflateEnd
    2>libOxygine-vc120-mt-gd.lib(pngread.obj) : error LNK2001: unresolved external symbol _inflateEnd
    2>libOxygine-vc120-mt-gd.lib(unzip.obj) : error LNK2001: unresolved external symbol _crc32
    2>libOxygine-vc120-mt-gd.lib(png.obj) : error LNK2001: unresolved external symbol _crc32
    2>libOxygine-vc120-mt-gd.lib(unzip.obj) : error LNK2001: unresolved external symbol _inflateInit2_
    2>libOxygine-vc120-mt-gd.lib(png.obj) : error LNK2001: unresolved external symbol _adler32
    2>libOxygine-vc120-mt-gd.lib(png.obj) : error LNK2001: unresolved external symbol _inflateReset
    2>libOxygine-vc120-mt-gd.lib(pngrutil.obj) : error LNK2001: unresolved external symbol _inflateInit_
    2>libOxygine-vc120-mt-gd.lib(pngwrite.obj) : error LNK2001: unresolved external symbol _deflateEnd
    2>libOxygine-vc120-mt-gd.lib(pngwutil.obj) : error LNK2001: unresolved external symbol _deflateReset
    2>libOxygine-vc120-mt-gd.lib(pngwutil.obj) : error LNK2001: unresolved external symbol _deflateInit2_
    2>libOxygine-vc120-mt-gd.lib(pngwutil.obj) : error LNK2001: unresolved external symbol _deflate

It seems to be having a problem finding zlib but this has been linked into libpng, which in turn was linked into the game library libOxygine.

My application itself is not directly dependant on both zlib and libpng so I dont really want to have to link to them directly from my application as it should be all taken care of inside my game engine library libOxygine.

Thanks

Upvotes: 0

Views: 4527

Answers (2)

daniel.bavrin
daniel.bavrin

Reputation: 86

If you used .vcxproj project from zlib package, it contains some bugs. here is instruction for fixing them (i used zlibvc, not zlibstat): http://www.tannerhelland.com/5076/compile-zlib-winapi-wapi-stdcall/

For fixing the unresolved symbols problem, open zlib project preferences, then go to Configuration Properties -> C/C++ -> Preprocessor, and in the Preprocessor Definitions line remove “ZLIB_WINAPI;” (don’t forget to remove the trailing semicolon).

Upvotes: 2

Glenn Randers-Pehrson
Glenn Randers-Pehrson

Reputation: 12445

libpng depends upon zlib, so you must link libpng first, then zlib. From your error messages it appears that you have them reversed. For example, if you are using gcc to build and link, you need "-lpng -lz" on the commandline, not "-lz ... -lpng".

Upvotes: 0

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