Bind Timer with a bool variable.

[JonB]

@thomasGl
In addition to @Christian-Ehrlicher.

Since there is QWidget::visible() and QWidget::setVisible(bool visible), which does the same as show/hide(), if you want you do not need to keep a boolean state variable (visible() already provides this). To toggle between shown and hidden your slot method or lambda for the QTimer can just do

this->setVisible(!this->visible());

E.g. make the QTimer a class member variable and

    connect(&timer, &QTimer::timeout, [this]() { this->setVisible(!this->visible()); });
    timer.start(2000);

[thomasGl]

Ok thx. Yes i want to hide and show it periodically.

[thomasGl]

Now i have another Problem. I want to increase the counter, when i click the button. Is there a way to display the counter? Because qDebug does not work.

int Button::ButtonclickedXtimes()
{
  count=0;
  

  if(this->clicked());  //does not work i need something like that.
  {
      count+=1;
      qDebug()<<count;
  }


}

[JonB]

@thomasGl said in Bind Timer with a bool variable.:

Is there a way to display the counter? Because qDebug does not work.

qDebug() does work, and qDebug()<<count; does work. Where it displays the output is a different matter, and depends on platform.

Depending on your needs to "display" this counter, you might use qDebug(), printf/fprintf(stderr or put it on a UI element such as a QLabel.

[SalemSabrehagen]

Did you #include <QDebug> ?
qDebug() messages should be visible in Qt Creater in the "output" tab
or external in a terminal if you set the hook "Run in terminal" in your project options.

[thomasGl]

Ok, thx i forgot to include <QDebug>

[thomasGl]

Hey Guys. Now i am trying to hide my label when my counter ist 5. My counter increases when i click the Button. I made a function where "this->hide(); <----"this" is my label. I am calling that function inside onother function in my Buttonclass, but the program crashes.

QObject::connect(this,SIGNAL(clicked(bool)),this,SLOT(ButtonclickedXtimes()));  //i am connecting the Button with the function for counting

void Button::ButtonclickedXtimes()   //slot function 
{
    Label* l;

   count++;
   qDebug()<<count;

   if(count==5)
   {
       l->labelhide();   //here i am calling the function for the label to hide.
   }


}
/*****************Label Class********************/

Label::Label(QWidget *parent):QLabel(parent)
{
    this->setGeometry(200,200,200,200);       
    this->setText("Hello World");        //i want that text to hide when counter is 5

    
 void Label::labelhide()    //thats my label hide function
{
    this->hide();
}

[Christian Ehrlicher]

@thomasGl said in Bind Timer with a bool variable.:

but the program crashes.

    Label* l;

   count++;
   qDebug()<<count;

   if(count==5)
   {
       l->labelhide(); 

I would be surprised if it would not crash.
The same as in your first post - you're using an unitialized pointer so what do you expect?

[thomasGl]

i initialized it with NULL , it crashes after 5 .

[Christian Ehrlicher]

@thomasGl said in Bind Timer with a bool variable.:

i initialized it with NULL , it crashes after 5 .

Are you kidding me?
It must be a valid pointer to your label you want to show or hide...

[JonB]

@Christian-Ehrlicher Listen, at least it is initialized... ;-)

[thomasGl]

@JonB said in Bind Timer with a bool variable.:

;-)

xD i got this thx guys.

[thomasGl]

Hi, how do i connect that button to the slots onclicked();?

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

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QMainWindow* wind = new QMainWindow();
    wind->resize(500,500);


    tWindow*z=new tWindow;

    //create Button
    QPushButton* butt = new QPushButton(wind);  
    butt->setText("click");


    QLabel* labb = new QLabel(wind);
    labb->setText("hello World");
    labb->setGeometry(200,200,200,200);

    //QObject::connect(button,SIGNAL(clicked(bool)),&a,SLOT(quit()));

    QObject::connect(butt,SIGNAL(clicked(bool)),tWindow,SLOT(onClicked())); //<-----this 

#include "twindow.h"

tWindow::tWindow(QWidget *parent):QMainWindow(parent)
{


}

tWindow::~tWindow()
{

}

void tWindow::onClicked()    //<----to this slot.
{
    qDebug()<<"HELLO";
}

[jsulm]

@thomasGl

connect(butt, &QPushButton::clicked, z, &tWindow::onClicked);

Please read https://doc.qt.io/qt-6/signalsandslots.html

[JonB]

@thomasGl said in Bind Timer with a bool variable.:

QObject::connect(butt,SIGNAL(clicked(bool)),tWindow,SLOT(onClicked())); //<-----this

Please do yourself a favor and only use New Signal Slot Syntax. "Old style" with SIGNAL/SLOT() macros is like a decade out of date nowadays!

QObject::connect(butt, &QPushButton::clicked, tWindow, &tWindow::onClicked);

It is then optional whether you make your tWindow::onClicked() method take the bool parameter --- if you don't care about the "checked" state you don't have to bother. A slot may have fewer parameters than the signal, but never more.

Having said this: your error is that tWindow is your class (shame you start it with a lowercase letter, very confusing), your instance is z so you will actually want

QObject::connect(butt, &QPushButton::clicked, z, &tWindow::onClicked);

[thomasGl]

i understand thx.

[thomasGl]

Because of Q_Object i am getting an error: undefined reference to vtable for lablos and error: Id returned 1 exit status. How can i fix that. I need Q_Object.

#ifndef LABLOS_H
#define LABLOS_H

#include <QLabel>

class lablos:public QLabel
{
    Q_OBJECT      //<----because of Q_Object i am getting an error..


public:
    lablos(QWidget* parent);


};

#endif // LABLOS_H

[Pl45m4]

@thomasGl

Re-run qmake / cmake after you added the Q_OBJECT macro

[thomasGl]

@Pl45m4 qmake / cmake? what do u mean?

[Pl45m4]

@thomasGl

You are using probably one of them. It's the build tool that "Makes" your code and builds your app / executable from your source code.

Especially when you add the QObject macro to some classes, you have to re-run it, to ensure that everything is updated. Sometimes your IDE (like QtCreator) notices, sometimes it doesn't.