link error when change configuration from Debug to Release

Question

Hi I have project In VC++ 2008 this project compile in debug mode without error but when I try to build it in release mode I get below linking erorr.

1>Linking...
1>LIBCMTD.lib(dbgheap.obj) : error LNK2005: __heap_alloc already defined in LIBCMT.lib(malloc.obj)
1>LIBCMTD.lib(dbgheap.obj) : error LNK2005: __recalloc already defined in LIBCMT.lib(recalloc.obj)
1>LIBCMTD.lib(dbgheap.obj) : error LNK2005: __msize already defined in LIBCMT.lib(msize.obj)
1>LIBCMTD.lib(malloc.obj) : error LNK2005: _V6_HeapAlloc already defined in LIBCMT.lib(malloc.obj)
1>LIBCMTD.lib(dbghook.obj) : error LNK2005: __crt_debugger_hook already defined in LIBCMT.lib(dbghook.obj)
1>LIBCMTD.lib(sbheap.obj) : error LNK2005: ___sbh_pHeaderDefer already defined in LIBCMT.lib(sbheap.obj)
1>LIBCMTD.lib(sbheap.obj) : error LNK2005: __get_sbh_threshold already defined in LIBCMT.lib(sbheap.obj)
1>LIBCMTD.lib(sbheap.obj) : error LNK2005: __set_sbh_threshold already defined in LIBCMT.lib(sbheap.obj)
1>LIBCMTD.lib(sbheap.obj) : error LNK2005: __set_amblksiz already defined in LIBCMT.lib(sbheap.obj)
1>LIBCMTD.lib(sbheap.obj) : error LNK2005: __get_amblksiz already defined in LIBCMT.lib(sbheap.obj)......

how I can fix it? thanks.

Answer 1

You're mixing VS runtimes - Make sure the "Project Properties/C++/Code Generation/Run-time Library" setting is the same for your project and all libraries you link to.

Answer 2

I had the same problem as you. Reason of this problem is that Linker include a lot of libraries that you dont see (for example you will include windows.h, it includes windef.h and so on...). And because these files are not idiot-proof written (#ifndef is missing) linker will try to #define same thing more times than once - problem.

My solution was setting this field: Project Properties -> Linker -> Input -> Ignore specific library

to "libcmt.lib"

With this your linker will ignore also in release configuration that problematic library that is included by default and everything should work.. :-)

Have a nice day.. :-)

P.S. If you want to avoid these linker misunderstandings, keep configuring project not in debug or release configuration, but in "All configuration". This option is on left upper corner of project configuration.