[英]When using fstream in a library I get linker errors in the executable
When I add当我添加
#include <fstream>
and try to use并尝试使用
std::ifstream (i.e. std::ifstream ifile(pDest))
in my library I get the following linker errors when compiling a project whih uses the library:在我的库中,编译使用该库的项目时出现以下链接器错误:
Error 2 error LNK2019: unresolved external symbol __CrtDbgReportW referenced in function "public: wchar_t * & __thiscall std::vector<wchar_t *,class std::allocator<wchar_t *> >::operator[](unsigned int)" (??A?$vector@PA_WV?$allocator@PA_W@std@@@std@@QAEAAPA_WI@Z) C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\Console.lib(ZipLib.obj) TestingZipper
Error 3 error LNK2001: unresolved external symbol __CrtDbgReportW C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\libcpmtd.lib(stdthrow.obj) TestingZipper
Error 4 error LNK2019: unresolved external symbol __free_dbg referenced in function "private: void __thiscall std::_Yarn<char>::_Tidy(void)" (?_Tidy@?$_Yarn@D@std@@AAEXXZ) C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\Console.lib(ZipLib.obj) TestingZipper
Error 5 error LNK2001: unresolved external symbol __free_dbg C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\libcpmtd.lib(xdebug.obj) TestingZipper
Error 6 error LNK2001: unresolved external symbol __free_dbg C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\libcpmtd.lib(locale0.obj) TestingZipper
Error 7 error LNK2019: unresolved external symbol __malloc_dbg referenced in function "void * __cdecl operator new(unsigned int,struct std::_DebugHeapTag_t const &,char *,int)" (??2@YAPAXIABU_DebugHeapTag_t@std@@PADH@Z) C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\libcpmtd.lib(xdebug.obj) TestingZipper
Error 8 error LNK2001: unresolved external symbol __malloc_dbg C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\libcpmtd.lib(locale0.obj) TestingZipper
Error 9 error LNK2019: unresolved external symbol __calloc_dbg referenced in function __Getctype C:\zipprojnotworking\CPP\7zip\UI\TestingZipper\libcpmtd.lib(_tolower.obj) TestingZipper Error 10 error LNK1120: 4 unresolved externals C:\zipprojnotworking\CPP\7zip\UI\Console\Debug\TestingZipper.exe TestingZipper
Any ideas why?任何想法为什么?
5+ years later... the problem (and maybe many others) is already solved (and forgotten :) ) 5 年后......问题(也许还有许多其他问题)已经解决(并被遗忘了:))
You have 1 lib project that contains the code above: I assume it's in a .c(xx) file and not in a .h file (included in both projects), and an app project that makes use of the previous one.您有 1 个包含上述代码的lib项目:我假设它在.c(xx)文件中而不是在.h文件中(包括在两个项目中),以及一个使用前一个的应用程序项目。
I've thought about what could the configuration that would yield this behavior be (the lib project building fine and the app project having these unresolved externals ) and the only configuration that stands up is: the lib project is not correct.我已经考虑过会产生这种行为的配置是什么(构建良好的lib项目和具有这些未解析的外部对象的应用程序项目),唯一站起来的配置是: lib项目不正确。 Let me detail:
详细说一下:
This is better that we can simplify the environment required for reproducing the behavior.这更好地我们可以简化重现行为所需的环境。 You can switch Project Properties -> Configuration Properties -> General -> Configuration Type and change from Static Library (.lib) to Dynamic Library (.dll) .
您可以切换Project Properties -> Configuration Properties -> General -> Configuration Type并从Static Library (.lib)更改为Dynamic Library (.dll) 。 Now, at the end it will link and will fail spitting the errors when building the lib project.
现在,最后它将链接并且在构建lib项目时将无法吐出错误。
1 Check [SO]: Errors when linking to protobuf 3 on MSVC 2013 for details about the CRT linking types (check the links as well). 1检查[SO]: Errors when links to protobuf 3 on MSVC 2013有关 CRT 链接类型的详细信息(也检查链接)。 Also check [SO]: LNK2005 Error in CLR Windows Form for more details about what happens when building C and C++ code.
另请查看[SO]:CLR Windows 窗体中的 LNK2005 错误,以获取有关构建C和C++代码时发生的情况的更多详细信息。
A few words about [MSDN.Blogs]: Debug vs Release builds: when building in Debug mode, some instrumentation code is silently added in your code to facilitate debugging.关于[MSDN.Blogs] 的几句话:调试与发布构建:在调试模式下构建时,一些检测代码会悄悄地添加到您的代码中以方便调试。 That's why Debug build artifacts ( vs their Release counterparts):
这就是为什么调试构建工件(与它们的发布版本相比):
The code addition is typically achieved by differences between build steps (simplified version):代码添加通常通过构建步骤(简化版)之间的差异来实现:
The most important thing is that the compile (and indirectly, preprocess) and link phases must be in sync .最重要的是编译(以及间接的预处理)和链接阶段必须同步。 This is not the case for your lib project, so you have an UCRT mismatch (as the 3rd comment states).
您的lib项目不是这种情况,因此您的UCRT不匹配(如第三条评论所述)。 To fix this, either :
要解决此问题,请执行以下任一操作:
I listed them both, since I don't know which one is incorrect (as you would want the configuration settings to match the configuration name ( Debug / Release )), but I have a feeling that it's the latter.我列出了它们,因为我不知道哪个不正确(因为您希望配置设置与配置名称( Debug / Release )相匹配),但我有一种感觉是后者。
Also, make sure to have consistent settings across projects that are supposed to work together.此外,请确保在应该协同工作的项目之间具有一致的设置。
for anyone like me that this answer did not ring helpful, a second option is to go to: Project Properties->Configuration Properties->General->Project Defaults->.NET Target Framework Version and set it to v4.0对于像我这样认为这个答案没有帮助的人,第二个选项是去:项目属性->配置属性->常规->项目默认值->.NET目标框架版本并将其设置为v4.0
https://connect.microsoft.com/VisualStudio/feedbackdetail/view/806238/unwarranted-linker-errors-using-stl-filestream-class-in-managed-classes-in-c-11-cli has an obscure answer from Microsoft team that fixed my issue. https://connect.microsoft.com/VisualStudio/feedbackdetail/view/806238/unwarranted-linker-errors-using-stl-filestream-class-in-managed-classes-in-c-11-cli有一个模糊的答案来自微软团队解决了我的问题。
I also added this answer to another version of the same problem.我还将此答案添加到同一问题的另一个版本中。
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