Question about Qcombo box < crash issue

[VRonin]

problem looks to be in: ui->descriptionLabel->setText(list[z]); almost surely because list is empty as I never saw you setting the user role to a QStringList anywhere in your code

[bask185]

@VRonin that is probably because I cannot find the words 'user' or 'role' anywhere on the doc.qt page and I don't understand how I can succesfully use a QStringClass for my purpose.

@all Nobody knows how I can display the description of my serial port???

[VRonin]

@bask185 said in Question about Qcombo box < crash issue:

I cannot find the words 'user' or 'role' anywhere on the doc.qt page

😕 http://doc.qt.io/qt-5/qcombobox.html#insertItem

Nobody knows how I can display the description of my serial port???

we do and we tried to explain you how. you have to save it in the data of the combobox

[bask185]

@VRonin I was looking on the QStringList page ...

I was doing that in an other function

for (QSerialPortInfo &info : infos) {
        QStringList list;

        list << info.portName();
        ui->serialPortBox->addItem(list.first(), list);
    }

So I was stuffing port names in the combo box, but not the description because that is not what I want. The descriptions are to be printed under the combobox in a text label.

So that function made me thinking, I made a new private QStringList variable called 'list2' and in the same function in which I fill the combobox I also fill 'list2' with dem descriptions

for (QSerialPortInfo &info : infos) {
        QStringList list;

        list << info.portName();
        list2 << info.description(); // < new line
        ui->serialPortBox->addItem(list.first(), list);
    }

so now I only had to do.

void Setup::on_serialPortBox_activated(const QString &arg1)
{
    z = ui->serialPortBox->currentIndex();

    ui->descriptionLabel->setText(list2[z]);
}

And voila:

[VRonin]

not how I would have done it but good enough for rock and roll

P.S.
I'd have done:

for (const QSerialPortInfo &info : infos) 
        ui->serialPortBox->addItem(info.portName(), info.description());

and then, in the constructor, added:
connect(ui->serialPortBox,static_cast<void(QComboBox::*)(int)>(&QComboBox::currentIndexChanged),[this](){ui->descriptionLabel->setText(ui->serialPortBox->currentData().toString();});

no need for QStringLists

[bask185]

dat looks rather.. exremely complicated compared to what I did O.o vague C++ syntax sometimes. Besides I really must avoid the use of pointers whenever possible, pointers are not good for my mental health -_-*

[VRonin]

[ambershark]

@bask185 said in Question about Qcombo box < crash issue:

Besides I really must avoid the use of pointers whenever possible, pointers are not good for my mental health

Lol, you may want to consider something other than C++. ;) I felt that way when I was first learning, but if you continue to feel that way, you really need a language that does it for you. Java, C#, python, tons of options. Python will even let you use Qt. :)

[bask185]

I was having a perfectly fine working application in processing. I shook dat code right out of my sleeve. Easy OO programming, no difficult vague words such as 'public' or 'private', no pointers, some easy global variables which I can use in every class I make. Truly processing is by far the easiest program ever :D

And do you know what it takes to export an application to Linux? Ctrl shift E, check Linux, press Export applications and BAM it works! Java ftw! But.... app was too heavy for my rpi... freakin java -_-". Now it takes me more than a week to crosscompile for the rpi. I had to install ubuntu on my Pc to find out I had only one 1GB space left so I had to delete my windows OS.... I do kinda regret I did not learn python and Tkinter first...

But the things I learn.. priceless

[ambershark]

@bask185 Yea java is just so slow and heavy. That's why I could never get into it.

I use an ide (CLion) that is written in java and it is so slow compared to the other one I use that is written in C++ (slickedit). I like CLion's features, but the java engine is just so slow. It's almost unusable on large projects, meanwhile slickedit has no speed issues.

Another anecdote.. I spun up an AWS micro server the other day to run upsource from jetbrains. It needed > 2GB in RAM just to start the application because of the java and cassandra dependency. If I wrote a similar application to upsource in something faster like C++ it would take maybe 50mb to start, not >2gb, lol. I killed the AWS server as I didn't want to pay for the bigger server just to mess around with upsource and installed it locally on a server in my office.

Morale of the story, java is great for easy, it does everything for you, programming, but it is awful when it comes to actually using the software that is produced, lol.