Unresolved externals in C++ when using vectors and find

问题

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:

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

__declspec(dllexport) double someFunc(double** Y, int length);

ERRORS

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...

回答1:

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

_DEBUG

defined either in your project settings (under C/C++ -- Preprocessor) or somewhere in your code (or include files).

It looks as if std::vector thinks you are building a debug build, when you are in fact creating a release build.

I hope this helps.

回答2:

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. The error is gone. Removing _DEBUG macro 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.

回答3:

The problem was I had _DEBUG defined in C/C++->Preprocessor. Changing it to NDEBUG solved the problem.

回答4:

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

来源：https://stackoverflow.com/questions/6003368/unresolved-externals-in-c-when-using-vectors-and-find

标签

c++

find

stdvector

unresolved-external