无效使用Qt类型不完整 [英] Invalide use of incomplete type Qt

问题描述

我有一个小问题:

finddialog.h

#ifndef FINDDIALOG_H
#define FINDDIALOG_H

class QDialog;
class QWidget;
class QLineEdit;
class QPushButton;
class QCheckBox;
class QLabel;

class FindDialog : public QDialog
{
    Q_OBJECT


public:
    FindDialog(QWidget *parent);

private slots:
    void findClicked();
    void enableFindButton(const QString &text);

signals :
    void findNext(const QString &str, Qt::CaseSensitivity cs);
    void findPrev(const QString &str, Qt::CaseSensitivity cs);

private:
    QLabel *findLabel;
    QLineEdit *textEdit;
    QCheckBox *caseCheckBox;
    QCheckBox *backwCheckBox;
    QPushButton *findButton;
    QPushButton *closeButton;

};

#endif // FINDDIALOG_H

finddialog.c

#include <QtWidgets>
#include "finddialog.h"


FindDialog::FindDialog(QWidget *parent) : QDialog(parent)
{
    QPushButton *button = new QPushButton(this);
}

void FindDialog::findClicked()
{

}

void FindDialog::enableFindButton(const QString &text)
{

}

我收到QDialog/QPushButton无效使用的不完整类型错误.

I receive a QDialog/QPushButton invalid use of incomplete type error.

我已经在.cpp文件中包含了QtWidget，为什么它不起作用?

I have already included QtWidget in .cpp file so why is it not working?

推荐答案

(转发)声明对于基类类型是不够的.您必须提供定义(使QDialog为完整类型)，所以:

(Forward) declaration is not enough for a base-class type. You have to provide the definition (make QDialog a complete type), so:

#include <QDialog>

头文件中的

.参见基类的前向声明.

根据您发布的代码，我不知道关于QPushButton不完整的错误来自何处(当然，如果您是#include <QtWidgets>).

Based on the code you posted, I don't know where the error about QPushButton being incomplete comes from (if you #include <QtWidgets>, of course).

如果不使用#include <QtWidgets>(具有#include <QPushButton>等)，则无法实例化这些不完整类型中的任何一种，如下所示:

If you do not #include <QtWidgets> (which has #include <QPushButton>, etc...), you cannot instantiate any of these incomplete types, like so:

new QPushButton(this);

这又需要一个定义(QPushButton需要的内存大小是多少?要调用什么构造函数?只有在该编译单元-.cpp文件中有定义的情况下才知道.)

That again, requires a definition (What's the size of the memory QPushButton needs? What constructor to call? That's known only if there's a definition in that compilation unit - .cpp file).

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