为什么我会收到符号查找错误？

Question

我正在编写一个库,它使用dlsym在我的主应用程序中动态加载.我有以下文件:

library.h

#include <ilibrary.h>
#include <igateway.h>

class LibraryImpl;

class Library: public ILibrary {
public:
    static ILibrary* instance();

    IGateway* getGateway() const;

protected:
    Library();
    virtual ~Library();

private:
    static ILibrary* instance_;
    LibraryImpl* library_;
};

extern "C" {
    IMPORT_EXPORT ILibrary* getLibrary();
}

library.cpp

#include "library.h"

#include "business/BCGateway.h"


class LibraryImpl {
public:
    IGateway* getGateway();
};

IGateway* LibraryImpl::getGateway() {
    return BCGateway::instance();
}



ILibrary* Library::instance_ = NULL;
ILibrary* Library::instance() {
    return instance_ ? instance_ : (instance_ = new Library);
}

Library::Library() {
    library_ = new LibraryImpl();
}

Library::~Library() {
    delete library_;
}

IGateway* Library::getGateway() const {
    return library_->getGateway();
}


extern "C" {
    IMPORT_EXPORT
    ILibrary* getLibrary(){
        return Library::instance();
    }
}

业务/ BCGateway.h

#include <igateway.h>

class BCGateway: public IGateway {
public:
    static IGateway* instance();

protected:
    BCGateway();

private:
    static IGateway* instance_;
};

业务/ BCGateway.cpp

#include "BCGateway.h"

IGateway* BCGateway::instance_ = NULL;
IGateway* BCGateway::instance(){
    return instance_ ? instance_ : (instance_ = new BCGateway);
}

我可以连接到库并成功加载Library-instance.但是当我在main-app中调用library-> getGateway()时,我收到以下错误:

符号查找错误:./ gateways/libSwisscomXtraZone.so:未定义的符号:_ZN9BCGateway8instanceEv

能否请你给我一个提示,我怎么解决这个问题？我被卡住了.

谢谢.

Answer 1

我把错误通过了c++filt,它说错误的名字代表

BCGateway::instance()

这表明你打电话BCGateway::instance()到某个地方并忘记链接BCGateway.o或甚至忘记定义BCGateway::instance().