“math.h”中的 _HUGE 和 __IMP__HUGE
我有一个关于 math.h 中定义的常量如何链接的问题。
在 Visual Studio 2010 中，我正在使用“MD”构建一个 64 位 dll C++ 库，该库使用使用“HUGE_VAL”的第三方库。从标题“math.h”来看，“HUGE_VAL”似乎被定义为“_HUGE”。当我尝试构建时，链接错误导致
错误 LNK2001: 无法解析的外部符号 _HUGE
经过一些谷歌搜索后，我认为 _HUGE 应该在 msvcrt.lib 中定义。 MSVCRT.lib已链接，但我没有链接libcmt.lib，因为它会导致重新定义错误。
让我感到奇怪的是，当我创建一个使用 HUGE_VAL 并使用 /verbose 作为链接器选项的简单控制台程序时，它显示 _IMP_HUGE 正在链接。
我真正好奇的是_HUGE在什么阶段变成_IMP_HUGE？另外，是否还有其他人遇到了未解决的 _HUGE 错误？是否有人对如何修复它有任何想法？
感谢您阅读这个长问题并提出任何想法。
I have a question about how constants defined in math.h are linked.
In visual studio 2010, I'm building a 64-bit dll c++ library with "MD" that uses a third party library that make use of "HUGE_VAL". From the header "math.h", it seems that "HUGE_VAL" is defined as "_HUGE". When I try to build, a linking error results
error LNK2001: unresolved external symbol _HUGE
After doing some googling, I think _HUGE should be defined in msvcrt.lib. MSVCRT.lib is linked, but I didn't link libcmt.lib because it would cause re-definition errors.
What strikes me as odd is that when I create a simple console program that uses HUGE_VAL and use /verbose as a linker option, it shows _IMP_HUGE being linked.
What I'm really curious of is at what stage does _HUGE turn into _IMP_HUGE? Also, have anyone else gotten the unresolved _HUGE error and does anyone have any ideas for how it could be fixed?
Thanks for reading the long question and for any ideas.
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我在VC11.0中遇到过这个问题。我得到的唯一错误是未解析的符号 _HUGE 错误。
我正在链接动态多线程运行时库，我发现如果我在链接步骤中包含“libcmt.lib”，那么问题就可以解决（或解决）。
我开始研究如何在 SDK 中定义标头来寻找线索，发现我在编译步骤中缺少编译器预目录：_DLL。
当您使用动态运行时库进行构建时，_HUGE 变量需要是 __declspec(dllimport)，以便可以找到它。当您包含“math.h”时 ->如果没有将 _DLL 设置为预指令，则“crtdefs.h”变量将不会被 __declspec(dllimport) 编辑，并且会在链接时显示缺失。
我遇到这个问题是因为我正在使用自己的自定义 makefile 进行编译，并且忽略了添加 _DLL 预指令。将 -D_DLL 添加到我的编译步骤解决了编译问题，无需其他更改。
我知道这个线程很旧，但我想我会把它扔在那里，因为它可能会帮助有类似问题的人。
I have experienced this issue with VC11.0. The only error I get is an unresolved symbol _HUGE error.
I am linking with dynamic multi-threaded run time libraries and I found that if I were to include "libcmt.lib" in my link step, then the issue is resolved (or worked around).
I started looking into how the headers were defined in the SDK for clues and found that I was missing a compiler pre-directory in my compile steps: _DLL.
When you build with dynamic run time libraries the _HUGE variable needs to be __declspec(dllimport) so it can be found. When you include "math.h" -> "crtdefs.h" without setting _DLL as a pre-directive, the variable will not be __declspec(dllimport)'ed and will appear missing at link time.
I was getting this issue because I am compiling with my own custom makefiles and I had neglected to add the _DLL pre-directive. Adding -D_DLL to my compilation step resolved the compile issue with no other changes needed.
I know this thread is old, but figured I would throw it out there as it may help someone with a similar issue.