使用向量和查找时 C++ 中未解析的外部变量
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Unresolved externals in C++ when using vectors and find
提问by MintGrowth
I have tried this code in a totally separate project, and it works fine (the only difference being that the project that is not working is being exported as a DLL). Here is the code:
我在一个完全独立的项目中尝试了这段代码，它运行良好（唯一的区别是不工作的项目被导出为 DLL）。这是代码：
RTATMATHLIB.CPP
RTATMATHLIB.CPP
#include "stdafx.h"
#include "RTATMATHLIB.h"
#include <math.h>
#include <vector>
#include <algorithm>
#include <stdexcept>
using namespace std;
double someFunc(double** Y, int length)
{
vector<double> myVector;
for(int i = 0; i < length; i++)
{
double value = (*Y)[i];
vector<double>::iterator it = find(myVector.begin(), myVector.end(), value);
if(it != myVector.end())
{
continue;
}
else
{
myVector.push_back(value);
}
}
return 0;
}
RTATMATHLIB.H
RTATMATHLIB.H
__declspec(dllexport) double someFunc(double** Y, int length);
ERRORS
错误
Error 1 error LNK2019: unresolved external symbol __imp___CrtDbgReportW referenced in function "public: __thiscall std::_Vector_const_iterator<double,class std::allocator<double> >::_Vector_const_iterator<double,class std::allocator<double> >(double *,class std::_Container_base_secure const *)" (??0?$_Vector_const_iterator@NV?$allocator@N@std@@@std@@QAE@PANPBV_Container_base_secure@1@@Z) RTATMATHLIB.obj RTATMATHLIB
Error 2 fatal error LNK1120: 1 unresolved externals
And that's it. I am not sure why it works in the other project and not this one...
就是这样。我不确定为什么它适用于另一个项目而不是这个项目......
回答by Lucky Luke
I found another forum post, where somebody seems to have reported the same exact problem that you are having. Please check to see if you have
我发现了另一个论坛帖子，其中似乎有人报告了与您遇到的完全相同的问题。请检查您是否有
_DEBUG
defined either in your project settings (under C/C++ -- Preprocessor) or somewhere in your code (or include files).
在您的项目设置（在 C/C++ -- Preprocessor 下）或在您的代码（或包含文件）中的某处定义。
It looks as if std::vector thinks you are building a debug build, when you are in fact creating a release build.
看起来 std::vector 认为您正在构建调试版本，而实际上您正在创建发布版本。
I hope this helps.
我希望这有帮助。
回答by cubuspl42
The problem in my case was a Debug configuration with Runtime Libraryset to Multi-threaded DLL. The fix was to change it to Multi-threaded Debug DLL. The error is gone. Removing _DEBUGmacro was also a kind of workaround, by I guess it's not a good idea because you end up with debug build linked to non-debug standard library.
在我的情况下，问题是Runtime Library设置为Multi-threaded DLL. 解决方法是将其更改为Multi-threaded Debug DLL. 错误消失了。删除_DEBUG宏也是一种解决方法，我想这不是一个好主意，因为您最终会得到链接到非调试标准库的调试版本。
回答by Yonatan Simson
The problem was I had _DEBUG defined in C/C++->Preprocessor. Changing it to NDEBUG solved the problem.
问题是我在 C/C++->Preprocessor 中定义了 _DEBUG。将其更改为 NDEBUG 解决了问题。
回答by Anurag Daware
Worked for me with : The problem in my case was a Debug configuration with Runtime Library set to Multi-threaded DLL. The fix was to change it to Multi-threaded Debug DLL
为我工作：在我的情况下，问题是运行时库设置为多线程 DLL 的调试配置。修复方法是将其更改为多线程调试 DLL
