Qt Signal Slot

gizalp

Hello everyone, I am very new at Qt C++ and trying to understand the logic of signal slot. What I wanted to implement is the following;
-When user on click the button, the external pyhton code that I wanted to run will be run.

I have seen this post --> http://www.qtforum.org/article/3773/when-pushbutton-click-qprocess-start.html?s=ddaff16695b9e225ee8a5f07c46f9e8d0f26d5df#post16206 .
Here is my code part;

public slots:
    void startProcess();

signals:
    void clicked();


connect(ui->button, SIGNAL(clicked()),this, SLOT(startProcess()));

void MainWindow::startProcess(){
    QProcess process;

            process.setWorkingDirectory("home/giz/Documents");
            process.setProgram("python helloworld.py");
            process.start("python helloworld.py");
            process.waitForFinished(1000);
}

When I run the code I am getting the following error;

QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()

Which one is wrong? My signal slot logic or qprocess usage?

joeQ

@gizalp hi,welcome friend.

connect(ui->button, &QPushButton::clicked,this, &MainWindow::startProcess);

or

connect(ui->button, SIGNAL(clicked()),this, SLOT(startProcess()));

mostefa

Hi @gizalp

Maybe somewhere on your code you have a slot named on_pushButton_clicked(), and this kind of name is used for QMetaObject::connectSlotsByName,

If you have a slot with the name on_pushButton_clicked() , try just to rename it to onPushButtonClicked() !

J.Hilk

@gizalp said in Qt Signal Slot:

When I run the code I am getting the following error;
QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()

Which one is wrong? My signal slot logic or qprocess usage?

seems like you created a pushbutton in QtDesigner, right cliked it and added Signal/Slot mechanismn that created a on_pushButton_clicked() function in your MainWindow class.
You either went and renamed the button in the designer-form or deleted the function or something like that.

However a clean rebuild should fix that for you

gizalp

@mostefa Thanks, that fixed my problem!

mostefa

@gizalp said in Qt Signal Slot:

@mostefa Thanks, that fixed my problem!

You are welcome =)