缺少带有 QObject 的派生类

Posted 2023-02-23

【中文标题】缺少带有 QObject 的派生类

【英文标题】：missing derived class with QObject

【发布时间】：2014-06-21 20:45:27

【问题描述】：

我收到错误 ~mainwindow.cpp:9: error: redefinition of 'MainWindow::MainWindow(QWidget*)' MainWindow::MainWindow(QWidget *parent) ：我很确定它在抱怨错误派生类名。基类是 MainWindow，但我看不出派生类是什么。

//主窗口.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QNetworkAccessManager>
#include <QUrl>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QImageReader>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

    ui->setupUi(this);


MainWindow::~MainWindow()

    delete ui;


void coreEng::requestPage()
    QUrl url("http://www.nyctelecomm.com");
    QNetworkReply* reply = nam->get(QNetworkRequest(url));


void coreEng::finishedSlot(QNetworkReply* reply)

    QVariant statusCodeV = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);

    QVariant redirectionTargetUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);

    if (reply->error() == QNetworkReply::NoError)
    

        QImageReader imageReader(reply);
        QImage pic = imageReader.read();

        QByteArray bytes = reply->readAll();  // bytes
        QString string(bytes); // string
    

    else
    

    

//    delete reply();



void MainWindow::on_lcdNumber_overflow()


    QByteArray replyData = netReply->readAll();


void MainWindow::on_pushButton_clicked()

    QObject::on_pushButton_clicked(nam, SIGNAL(finished(QNetworkReply*)),
    this, SLOT(finishedSlot(QNetworkReply*)));

//主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QObject>
#include <QNetworkAccessManager>

namespace Ui 
class MainWindow;


class MainWindow : public QMainWindow

    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0):
    QMainWindow(parent)
        
            nam = new QNetworkAccessManager();
        
    ~MainWindow();

private:
    Ui::MainWindow *ui;

public slots:
    //void connect();
    void on_pushButton_clicked();
    void requestPage();
    void finishedSlot(QNetworkReply* reply);
private slots:
    void on_lcdNumber_overflow();

private:
    QNetworkAccessManager* nam;

;

#endif // MAINWINDOW_H

//main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])

    QApplication a(argc, argv);

    MainWindow mConnect;
    mConnect.on_pushButton_clicked();
    mConnect.requestPage();

    MainWindow w;
    w.show();

    return a.exec();

【参考方案1】：

您已经定义了两次MainWindow::MainWindow。第一个在头文件中，第二个在源文件中。这是错误消息中所说的。

explicit MainWindow(QWidget *parent = 0):
QMainWindow(parent)
    
        nam = new QNetworkAccessManager();
    

//

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

    ui->setupUi(this);