[Qt]：'CButton‘没有命名类型

Question

我的代码有问题。编译器一直显示我创建的每个CButton指针都有此错误。

/home/trafel/ドキュメント/Projects/C++/CCalc/ccalc.h:23: error : 'CButton' does not name a type
     CButton *button_0;
     ^

CButton类从QPushButton扩展而来。以下是主标题的代码：

#ifndef CCALC_H
#define CCALC_H

#include <QWidget>
#include <QMainWindow>
#include <QPushButton>
#include "clabel.h"
#include "cbutton.h"

class CCalc : public QMainWindow
{
    Q_OBJECT

public:
    CCalc();
    ~CCalc();

public slots:
    void CPush(QString);
    void CAction(QString);

private:
    CButton *button_0;
    CButton *button_1;
    CButton *button_2;
    CButton *button_3;
    CButton *button_4;
    CButton *button_5;
    CButton *button_6;
    CButton *button_7;
    CButton *button_8;
    CButton *button_9;
    CButton *button_equal;
    CButton *button_plus;
    CButton *button_minus;
    CButton *button_multiply;
    CButton *button_divide;
    CButton *button_power;
    CButton *button_root;
    CButton *button_leftParenthesis;
    CButton *button_rightParenthesis;
    CButton *button_return;
    CButton *button_ce;

    CLabel  *label_input;
    CLabel  *label_output;

    QMenu *menu_session;
        QAction *session_new;
        QAction *session_open;
        QAction *session_save;
        QAction *session_quit;
    QMenu *menu_log;
        QAction *log_inspect;
    QMenu *menu_help;
        QAction *help_help;
        QAction *help_about;
};

#endif // CCALC_H

这是来自CButton类头的：

#ifndef CBUTTON_H
#define CBUTTON_H

#include <QPushButton>
#include "ccalc.h"

class CButton : public QPushButton
{
    Q_OBJECT

public:
    CButton(QWidget *parent);
    ~CButton();
    QString getValue();
    void setValue(QString string);

private:
    QString value;
};

#endif // CBUTTON_H

我忘了加什么东西了吗？

Answer 1

简短解决方案：

在文件"cbutton.h"中替换：

#include "ccalc.h"

通过以下方式：

class CCalc;

或者完全删除该#include，因为看起来您无论如何都不使用它。

解释：

注意，您有循环依赖关系:在"ccalc.h"中，您需要知道CButton是什么，而在"cbutton.h"中，您需要知道CCalc是什么。

这意味着，如果首先解析"cbutton.h"，您将按以下顺序点击这些行(只显示相关行)：

1. #define CBUTTON_H      <-- from file "cbutton.h"
2. #include "ccalc.h"     <-- from file "cbutton.h"
3. #include "cbutton.h"   <-- from file "ccalc.h", but as CBUTTON_H is already defined, the content of this file is ignored.
4. CButton *button_0;     <-- from file "ccalc.h", which indeed refers to an undefined class, as we have not reached the line "class CButton" yet.

这些情况下的解决方案是，如果在"ccalc.h"中不需要知道"cubutton.h"中的方法，而只需要知道类的存在，就可以用类原型class CButton;替换包含的方法。#include "clabel.h"和#include "clabel.h"也是如此。