Creating events that trigger own functions

adamchalkley2018

hey guys I have two questions first off my code doesn't seem to be working it is telling me that MainWindow does not have a member called pushButton_2 but that is strange since I call ui->pushButton_2->setText(); above it

#include <iostream>
#include "mainwindow.h"
#include "ui_mainwindow.h"


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->pushButton->setText("hello");
    ui->pushButton_2->setText("hello world 2");
    std::cout << "hello from the console" << std::endl;
    printHello();
    connect(ui->pushButton_2,SIGNAL(pressed()),ui->pushButton_2,SLOT(update())); // error
    
}

void MainWindow::printHello()
{
    std::cout << "\n";
    std::cout << "hello from printHello() function" << std::endl;
    delete ui;
}


MainWindow::~MainWindow()
{
    delete ui;
}

header

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

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

my second question is how do you call a function when you trigger an event say I click one of the buttons I would like my printHello() function to be called ,

sorry if I didn't format this properly couldn't find any code tags

thanks

SGaist

Hi,

From here it looks correct. Are you sure that in your original code both names a correct ?

By the way, why call your button update slot when you press on it ?

Make printHello a slot and connect it to the clicked signal of the push button of your choice.

adamchalkley2018

seems to compile now,don't know why it was not earlier

2

connect(ui->pushButton,SIGNAL(clicked()),ui->pushButton,SLOT(printHello()));

I created a slot called printHello() and used the following code,but when I click on the button nothing happens,text should appear in the console window

thanks

SGaist

Why are you deleting ui in printHello ?

printHello is a member of MainWindow not of your other push button.

Depending on your setup, it might get shown once you end your application.

You can use qDebug() for your testing.

adamchalkley2018

my bad I noticed that too that is a big no no haha

yeah its strange the way printHello() isn't appearing

SGaist

Do you have any runtime warning ?

On a side note, if you switch to the new syntax using function pointers, you'll have compile time checks rather than runtime checks for your connections.