Question

我正在尝试编译多个.cpp和.h文件。但它显示错误。

我的档案是：

ApplicationWindow.cpp

#include "ApplicationWindow.h"

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

ApplicationWindow.h

#ifndef APPLICATION_WINDOW_H
#define APPLICATION_WINDOW_H

#include "Window.h"

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

#endif /* APPLICATION_WINDOW_H */

window.h中

#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 */

Window.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;
}

我还有WindowImp.h和WindowSystemFactory.h文件。

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

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)

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。但我试图链接所有其他.cpp和.h文件的方式回答上面我在这里粘贴的链接。提前感谢....

Answer 1

您在Window中声明了许多虚函数。标题，但您没有定义任何实现。

您可以编译每个.cpp文件，因为那里没有语法错误。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

只需先隐藏您未使用的所有虚拟功能，然后再定义，然后重试。（或者向它们添加空实现）

如何使用gcc / g ++编译多个cpp文件头文件？