Convert data from QLineEdit to QString when a QPushButton is clicked. - c++

Question

This site is trully amazing I would like to thanks anyone who answers my post. You would probably find my post a repost of a repost since it's again about retreive data from a QLineEdit. I've been trying to fix the problem for 2 entire days looking throught the hudge stackoverflow database but I can't find a answer.
Basically I want to retreive an ip address from a QLineEdit and a port number from a QLineEdit to do so I do :
myclass::myclass(QWidget *parent = 0)
{
_mainuilayout = new QGridLayout();
ipAddress = new QLineEdit();
portnumber = new QLineEdit();
QFormLayout *connect2adress = new QFormLayout();
connect2adress->addRow("Ip Adress : ", ipAddress);
connect2adress->addRow("Port number : ", portnumber);
_launch = new QPushButton("Launch server");
_mainuilayout->addWidget(_launch);
_mainuilayout->addLayout(connect2adress);
QObject::connect(_launch, SIGNAL(clicked()), this, SLOT(setipAddress()));
QObject::connect(_launch, SIGNAL(clicked()), this, SLOT(setportnumber()));
server->connectTo(thisaddress,thisport);
QObject::connect(_launch, SIGNAL(clicked()), server, SLOT(launchserver()));
}
Here you got the code to store the ip address in a QString thisaddress is a QString defined in the header as well as thisport
void myclass::setipAddress()
{
thisaddress = ipAddress->text();
}
void myclass::setportnumber()
{
thisport = portnumber->text().toShort();
}
What I want is when I click on launch button it store the data from QLineEdit in thisaddress and in thisport so I can launch the server, here is the code for connectTo
void server::connectTo(QString ipAdress,quint16 port)
{
if(!ipAdress.isEmpty() && port != 0 )
{
ipAddress = ipAdress;
portnumber = port;
}
}
The problem is really coming when I convert QLineEdit to QString because when I directly assign thisAddress and thisportnumber like that it's working
thisAddress = "127.0.0.1"
thisportnumber = 5855
Overwise I got this error :
Unsupported socket Operation
So guys do you have any answers to help me ?
I've tried to follow the solution given in that stack post Store QLineEdit's data into a QString upon a QPushButton click
but it still not working I'm still working on it if I find something I let you know !
Thanks for the replies !

Answer 1

It has been ages since I used Qt, but I see nobody has answered your question so I'll add my two cents.
I don't think you can expect a specific call order when you connect an event to multiple slots. You are connecting clicked() event on the _launch button to populate your IP address and port number, and also to call launchserver(). But you require the other two slots to be called first.
It would be better if you can just connect it to a single slot, which will update the appropriate member values and then do the connect.

Answer 2

It looks like I'm either missing something, or there is confusion about what exactly is happening in the connect calls. The connect function only tells Qt what to do when a signal is emitted (usually when the user does something). It does not wait for that event to happen.
myclass::myclass(QWidget *parent = 0)
{
// <snipped construction and layout>
// Tell Qt what to do when the clicked signal happens:
QObject::connect(_launch, SIGNAL(clicked()), this, SLOT(setipAddress()));
QObject::connect(_launch, SIGNAL(clicked()), this, SLOT(setportnumber()));
// At this point, nothing has been set, because the user hasn't had time to
// fill in anything -- you've only told the application what to do when they
// do so.
server->connectTo(thisaddress,thisport);
// As pointed out previously, even though you're telling the application what
// to do, the application says nothing about the order, so you don't know if
// this will be run before or after the slots to set the ip address and port
// number.
// What you do know is that it won't be run before the previous line of code,
// which does the first connection.
QObject::connect(_launch, SIGNAL(clicked()), server, SLOT(launchserver()));
}
The following is a more straightforward implementation:
myclass::myclass(QWidget *parent = 0)
{
_mainuilayout = new QGridLayout();
_ipAddress = new QLineEdit();
_portnumber = new QLineEdit();
QFormLayout *connect2adress = new QFormLayout();
connect2adress->addRow("Ip Adress : ", ipAddress);
connect2adress->addRow("Port number : ", portnumber);
_launch = new QPushButton("Launch server");
_mainuilayout->addWidget(_launch);
_mainuilayout->addLayout(connect2adress);
QObject::connect(_launch, SIGNAL(clicked()), server, SLOT(launchserver()));
}
myclass::launchserver()
{
server->connectTo(_ipAddress->text(),_portnumber->text().toShort());
}