c++ - 如何使用gcc/g++编译多个cpp文件的头文件？

Question

我正在尝试编译多个 .cpp 和 .h 文件。但它显示错误。

我的文件是:

应用程序窗口.cpp

#include "ApplicationWindow.h"

void ApplicationWindow::DrawContents ()
{
  GetView()->DrawOn(this);
}

应用程序窗口.h

#ifndef APPLICATION_WINDOW_H
#define APPLICATION_WINDOW_H

#include "Window.h"

class ApplicationWindow : public Window
{
public:
    // ...
    virtual void DrawContents();
};

#endif /* APPLICATION_WINDOW_H */

窗口.h

#ifndef WINDOW_H
#define WINDOW_H

#include "View.h"

class Point;
class WindowImp;

class Window {
public:
    Window(View* contents);

    // requests handled by window
    virtual void DrawContents();

    virtual void Open();
    virtual void Close();
    virtual void Iconify();
    virtual void Deiconify();

    // requests forwarded to implementation
    virtual void SetOrigin(const Point& at);
    virtual void SetExtent(const Point& extent);
    virtual void Raise();
    virtual void Lower();

    virtual void DrawLine(const Point&, const Point&);
    virtual void DrawRect(const Point&, const Point&);
    virtual void DrawPolygon(const Point[], int n);
    virtual void DrawText(const char*, const Point&);

protected:
    WindowImp* GetWindowImp();
    View* GetView();

private:
    WindowImp* _imp;
    View* _contents; // the window's contents
};

#endif /* WINDOW_H */

窗口.cpp

#include "Window.h"
#include "WindowImp.h"
#include "WindowSystemFactory.h"

void Window::DrawRect (const Point& p1, const Point& p2) {
    WindowImp* imp = GetWindowImp();
    imp->DeviceRect(p1.X(), p1.Y(), p2.X(), p2.Y());
}

WindowImp* Window::GetWindowImp () {
    if (_imp == 0) {
        _imp = WindowSystemFactory::Instance()->MakeWindowImp();
    }
    return _imp;
}

View .h

#ifndef VIEW_H
#define VIEW_H

class ApplicationWindow;

class View {
public:
    void DrawOn(const ApplicationWindow* w) const;
};

#endif /* VIEW */

View .cpp

#include "View.h"
#include <iostream>
using namespace std;

void View::DrawOn(const ApplicationWindow* w) const
{
    cout << "DrawOn(" << w << ")" << endl;
}

我也有 WindowImp.h 和 WindowSystemFactory.h 文件。

我尝试了从其他 stackoverflow 答案中找到的所有方法 ( Using G++ to compile multiple .cpp and .h files 。

但它显示以下错误:

"Window::DrawPolygon(Point const*, int)", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::Open()", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::Close()", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::Lower()", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::Raise()", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::GetView()", referenced from:

  ApplicationWindow::DrawContents() in ApplicationWindow.o

"Window::Iconify()", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::DrawLine(Point const&, Point const&)", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::DrawRect(Point const&, Point const&)", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::DrawText(char const*, Point const&)", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::Deiconify()", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::SetExtent(Point const&)", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"Window::SetOrigin(Point const&)", referenced from:

  vtable for ApplicationWindow in ApplicationWindow.o

"View::DrawOn(ApplicationWindow const*) const", referenced from:

  ApplicationWindow::DrawContents() in ApplicationWindow.o

"typeinfo for Window", referenced from:

  typeinfo for ApplicationWindow in ApplicationWindow.o

ld: symbol(s) not found for architecture x86_64

clang: error: linker command failed with exit code 1 (use -v to see invocation)

还有我的g++ --version

Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.3.0
Thread model: posix

我使用的是 Mac OSX 10.9.4。我知道这是上述答案的重复，但我仍然无法解决。如果有人帮助我，那对我来说会很棒。

我必须运行 g++ ApplicationWindow.cpp 文件而不会出现上述错误。但我尝试按照我在此处粘贴的上述链接的回答中提到的方式链接所有其他 .cpp 和 .h 文件。提前致谢....

Answer 1

你在你的窗口中声明了很多虚函数。 header ，但您没有定义任何实现。

您可以编译每个 .cpp 文件，因为其中没有语法错误。但是，链接器无法找到您声明的函数，因此无法生成可执行文件。

http://www.parashift.com/c++-faq/link-errs-missing-vtable.html

只需先隐藏所有未使用且未定义的虚函数，然后再试一次。 (或向它们添加空实现)