blocks|key|2755658|text|这样的错误通常意味着您还没有将类的头添加到pro文件中的“header”变量中(元对象编译器只为该变量中列出的标题生成moc_文件)。记得在更改.pro文件后运行qmake！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2755659|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Such errors usually mean that you haven't added the header of your class to "HEADERS" variable in pro file (meta object compiler generates moc_ files only for headers listed in this variable). Remember to run qmake after you change .pro file!

blocks|key|1347435|text|我有一个类似的问题，它解决了使用andref的反馈。在中，我简单地说：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1347436|qmake|1347437|Build/Run|unordered-list-item|1347438|
+/|1347439|构建/清除所有|ordered-list-item|1347440|生成/运行|1347441|1347442|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|T|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|U|8|@]|9|@]|A|$]]|$1|L|3|M|5|K|7|V|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|W|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|P|$]]

I had a similar problem and it was solved using andref's feedback. Within QT Creator I simply:

<ol>
<li>Build/Clean all</li>
<li>Build/Run qmake</li>
<li>Build/Run</li>
</ol>

blocks|key|2799897|text|每当您更改QObject继承时，一定要执行clean，然后是qmake，然后是build。qmake很重要，因为它更新.h文件中任何新的Qt更改(包括QObject继承，即Q_OBJECT+)的moc*文件。实际上，在某些情况下，您甚至可以简单地执行qmake然后build来进行增量构建。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2799898|entityMap^0|L|5|U|5|13|5|19|5|2E|8|3H|5|3O|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|G|$]]

Whenever you change QObject inheritance be sure to do a <code>clean</code>, <code>qmake</code> then <code>build</code>. The <code>qmake</code> is important since it updates moc* files for any new Qt changes in your .h files including QObject inheritance, ie <code>Q_OBJECT</code>. In fact, in some cases, you may even be able to simply do <code>qmake</code> then <code>build</code> for an incremental build.

blocks|key|2799691|text|签入文件MakeFile.debug，可能HIMyClass不存在。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2799692|我只是重命名MakeFile.debug，清理项目并重新构建所有，然后它就编译了。|2799693|entityMap^0|4|E|L|9|0|6|E|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|R|8|@]|D|@]|E|$]]]|I|$]]

Check in the file <code>MakeFile.debug</code> and maybe <code>HIMyClass</code> don't exists.

I just rename <code>MakeFile.debug</code>, Clean the Project and Rebuild All and it compiles.

blocks|key|2799835|text|我也遇到了同样的问题，但在我的例子中，仅仅清理->构建是不够的。因此，我不得不手动删除在构建过程中创建的所有文件(Mekefiles、cpp中的ui描述符，以及一般由build+process创建的整个目录)，直到生成成功。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2799836|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I had the same problem but in my case it wasn't enough to clean -> build. So I had to delete manually all files created in build process (Mekefiles, ui descriptionns in cpp, and generally whole directory created by build process) and only then build succeded.

blocks|key|2755641|text|检查pro文件中是否有必要的Qt配置选项(至少QT+%2B=+core+gui)。还要尝试手动删除在build目录中生成/创建的所有内容。有时，由于某种原因，moc无法运行。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2755642|您还可以自己尝试运行moc命令，并查看它的输出(您可以在QtCreator中的“编译输出”选项卡中找到命令行)。|2755643|更新:与this相关的问题似乎表明您在编译时没有定义QT_DLL。您能否尝试一个新的、新的简单QtCreator项目(例如，带有子类mainwindow的小部件)并进行尝试。它应该自动包含一个Q_OBJECT头，并尝试比较.pro文件和编译器输出。|2755644|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/2022174/qt-vs2005-qwt-cant-use-q-object-in-class-derived-from-qwt-widgets^0|N|E|25|3|0|0|4|4|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@]|D|@$9|Y|A|Z|1|10]]|E|$]]|$1|J|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

Check that the necessary Qt config options are present in the pro file (<code>QT += core gui</code> at least. Also try manually deleting everything built/created in the build directory. It sometimes happens that <code>moc</code> fails to run for some reason.

You can also try running the moc command yourself, and see what it outputs (you can find the command line in the tab "Compile output" in QtCreator.

UPDATE: <a href="https://stackoverflow.com/questions/2022174/qt-vs2005-qwt-cant-use-q-object-in-class-derived-from-qwt-widgets">this</a> related problem seems to suggest you don't define QT_DLL when compiling. Can you try a fresh and new simple QtCreator project (with a widget that subclasses mainwindow for example) and try that. It should contain a Q_OBJECT header automatically and try to compare the .pro files and compiler output.

blocks|key|2755823|text|在我的osx盒里，这是因为丢失了moc*文件。我通过从utf-8编码的.pro文件中删除bom来修正这个问题。我将向qt提交一个bug。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2755824|护目镜搜索错误。注意:缺少的vtable通常意味着第一个非内联虚拟成员函数没有定义。|2755825|2755826|+"vtable+for+MainWindow"，引用于：|blockquote|2755827|2755828|MainWindow：：MainWindow(QWidget*)在mainwindow.o中|2755829|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|O|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|P|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|L|$]]

on my osx box this was due to missing moc* files.
i fixed this by removing the bom from my utf-8 encoded .pro file.
i will file a bug with qt.
error for goggle searches...
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
<blockquote>
&quot;vtable for MainWindow&quot;, referenced from:
<pre><code> MainWindow::MainWindow(QWidget*)in mainwindow.o
</code></pre>
</blockquote>

blocks|key|1347503|text|我发现了另一个可能的原因并解决了这个错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1347504|如果已在.h文件中声明槽，但未在实现中定义其主体，则也会发生此错误。|1347505|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I found another possible cause and solution to this error

This error will also occur if one has declared the slot in .h file but has not defined its body in the implementation

blocks|key|2799908|text|我有这个问题。验证是否对.cpp文件中的插槽的实现有描述。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2799909|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I had this problem. 
Verify whether there is a description of the implementation of the slot in .cpp file.

blocks|key|1346090|text|我从我的主文件中删除了#include+"main.moc"，忘了重新添加它.那是一个有趣的时间浪费！|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1346091|entityMap^0|B|J|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

I had removed <code>#include "main.moc"</code> from my main file, and forgot to re-add it... That was a fun time-waster!

blocks|key|1347544|text|查洛普和艾拉克斯的回答帮助了我。我不得不关闭Qt创建者并再次打开它，尽管qmake才能生效。我遵循以下步骤:+1.将类定义移动到头文件。2.将头文件添加到项目中，并确保在%2B=文件中的头文件中列出头文件。3.清除所有4.关闭QtCreator+(在Windows+10上)+5.从项目目录6中删除Makefile。打开QtCreator并打开项目。7.+Qmake以确保生成makefile。8.重建-一切|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1347545|这些步骤帮助我解决了这个问题--我为各种其他的答案和方法奋斗了一个多小时，没有什么效果。在运行qmake之前，请确保删除makefile并关闭QtCreator+(至少适用于windows+10)。|1347546|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Answers from @chalup and @ierax helped me. I had to close the Qt creator and open it again though for qmake to take effect. I followed these steps:
1. Moved the class definition to a header file. 
2. Added header file to project and ensured it is listed against HEADERS += \ list in .pro file.
3. Clean-all 
4. close QtCreator (on Windows 10)
5. Delete Makefiles from the project directory
6. Open QtCreator and open the project.
7. Qmake to ensure makefiles are generated.
8. Rebuild-all 

These steps helped me solve this issue - I struggled for over an hour with various other answers and methods nothing worked. Before you run qmake ensure you delete makefiles and close QtCreator (applicable atleast on windows 10).

I am receiving the following linker error when I build my application.

<blockquote>
 HIMyClass.obj:: error: 
 unresolved external symbol "public:
 virtual struct QMetaObject const *
 __thiscall CHIMyClass::metaObject(void)const
 "
 (?metaObject@CHIMyClass@@UBEPBUQMetaObject@@XZ)
 File not found : HIMyClass.obj
 
 HIMyClass.obj:: error: 
 unresolved external symbol "public:
 virtual void * __thiscall
 CHIMyClass::qt_metacast(char
 const *)"
 (?qt_metacast@CHIMyClass@@UAEPAXPBD@Z) File not found : HIMyClass.obj
 
 HIMyClass.obj:: error: 
 unresolved external symbol "public:
 virtual int __thiscall
 CHIMyClass::qt_metacall(enum
 QMetaObject::Call,int,void * *)"
 (?qt_metacall@CHIMyClass@@UAEHW4Call@QMetaObject@@HPAPAX@Z) File not found : HIMyClass.obj
</blockquote>

My class declaration is like 

<pre><code>class CHIMyClass:public QDialog
{
 Q_OBJECT

 ....

};
</code></pre>

When I comment Q_OBJECT the linker error goes off (and obviously I am not able to use signals and slots). I am using Qt Creator as IDE and Qt 4.5.3. When I give Rebuild All it's definite that QMake will be called. I guess that, its the generation of moc_* files is where the problem lies. I am using Windows XP and cl as the compiler.

What might be the reason behind this linker error?

Q_OBJECT linker error!

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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当我构建我的应用程序时，我收到下面的链接程序错误。错误:未解决的外部符号"public： struct QMetaObject const * __thiscall CHIMyClass：：元对象(无效)const“文件未找到: HIMyClass.objHIMyClass.obj:：错误:未解决的外部符号"public: virtual * __thiscall CHIMyClass：：qt_m

问Q_OBJECT链接器错误！
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问Q_OBJECT链接器错误！
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