我在Windows上使用Qt 5並構建具有多個QDialog類的GUI應用程序。我試圖在QMainWindow類的一個觸發動作中創建一個QDialog的實例後,連接一個信號。我在這裏閱讀了關於Qt的文檔:http://doc.qt.io/qt-4.8/signalsandslots.html和這裏:https://wiki.qt.io/New_Signal_Slot_Syntax。我也閱讀了很多關於stackoverflow的問題,這些問題幫助我糾正了一些最初的錯誤,但並沒有幫助我解決這個問題。Qt - 在觸發的動作中連接信號/插槽
我不斷收到的錯誤是:
「之前的預期‘’令牌主表達式」
我曾經嘗試都舊語法連接
connect(sender, SIGNAL (valueChanged(QString,QString)),
receiver, SLOT (updateValue(QString)));
和新語法(顯示在下面的.cpp文件中)
connect(sender, &Sender::valueChanged,
receiver, &Receiver::updateValue);
MainWindow創建成i在main.cpp和第二個對話框中創建on_action_someAction_triggered(),所以我知道我所引用的實例存在。有沒有更好的方式來連接信號和SLOT?
這是我正在使用的代碼(減去額外的無關代碼)。
主窗口的.h:
#include <QMainWindow>
#include "shipdia.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
public slots:
void loadSelectedShip(QString shipName);
private slots:
void on_actionNew_Ship_triggered();
private:
Ui::MainWindow *ui;
shipdia *sDialog;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QTextStream>
#include <QObject>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_actionNew_Ship_triggered()
{
sDialog = new shipdia(this);
QObject::connect(&shipdia, //this is were I attempt to
&shipdia::sendShip, //connect the signal/slot
this,&MainWindow::loadSelectedShip); //but always get an error
sDialog ->show();
}
void MainWindow::loadSelectedShip(QString shipName)
{
... do something ... //this code works, but the signal is never received
}
qdialog.h
#ifndef SHIPDIA_H
#define SHIPDIA_H
#include "functions.h"
#include <QDialog>
namespace Ui {
class shipdia;
}
class shipdia : public QDialog
{
Q_OBJECT
public:
explicit shipdia(QWidget *parent = 0);
~shipdia();
private slots:
void on_pushButton_2_clicked();
signals:
void sendShip(QString shipName);
private:
Ui::shipdia *ui;
};
#endif // SHIPDIA_H
qdialog.cpp
#include "shipdia.h"
#include "ui_shipdia.h"
#include <QObject>
#include <QMessageBox>
#include <QTextStream>
#include <QDir>
shipdia::shipdia(QWidget *parent) :
QDialog(parent),
ui(new Ui::shipdia)
{
ui->setupUi(this);
}
shipdia::~shipdia()
{
delete ui;
}
void shipdia::sendSelectedShip(QString shipName)
{
emit sendShip(shipName); //I previously just emitted sendSelectedShip,
//but separating the function did not fix it.
}
void shipdia::on_pushButton_2_clicked()
{
//Code below functions up to next comment
QString shipName = ui->line_23->text();
shipName = QDir::currentPath() + "/shipFolder/" + shipName + ".txt";
QFile shipFile(shipName);
QStringList stringList;
if (shipFile.open(QIODevice::ReadOnly))
{
QTextStream in(&shipFile);
while(!in.atEnd())
{
QString line = in.readLine();
if(line.isNull())
break;
else
stringList.append(line);
}
shipFile.close();
}
//Code above functions^
sendSelectedShip(shipName); //this line does not produce an error
}
'shipdia'是一種類型(如果'新船'...是相信的)。 'connect(&shipdia,...)'因此沒有任何意義。你可能意思是'connect(sDialog,...)' –