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Thread: signal and slots problem

  1. #1
    Join Date
    Apr 2017
    Qt products

    Default signal and slots problem

    hi i have a mainwindow.ui that has one QLineEdit named nodes and also a pushButton...and i have a secwindow.ui with two QLineEdit named nodes1, nodes2

    what i want to do is when a entering a certain number in nodes, let's say "1" so i would want to make nodes1 empty and nodes2 has a text as "Null".

    my problem is where to put my if statment that include all three line edits?

    Qt Code:
    1. ....
    2. public:
    3. SecWindow *secwindow;
    5. signals:
    6. void nodes(const QString &text); //my signal for nodes
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    Qt Code:
    1. void MainWindow::on_pushButton_clicked()
    2. {
    3. secwindow = new SecWindow(this);
    4. connect(nodes,&QLineEdit::textChanged,secwindow,&SecWindow::nodes1); //a connect between nodes
    5. QString number_of_nodes = ui->nodes->text(); //and nodes1
    7. if(number_of_nodes == "1"){ // i cant put a condition
    8. } // between nodes and nodes1
    10. secwindow->show();
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    Qt Code:
    1. ......
    2. public slots:
    3. void nodes1(const QString &text);
    4. void nodes2(const QString &text);
    5. private slots:
    6. void on_pushButton_clicked();
    8. void on_nodes1_textChanged(const QString &arg1);
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    Qt Code:
    1. void SecWindow::nodes1(const QString &text) // still confused how or where to put the if statment
    2. {
    3. }
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    so am not very clear where to add my if stament in mainwindow.cpp
    or secwindow.cpp

    please help me

  2. #2
    Join Date
    Jan 2006
    Munich, Germany
    Thanked 418 Times in 411 Posts
    Qt products
    Qt3 Qt4 Qt5 Qt/Embedded
    Unix/X11 Windows

    Default Re: signal and slots problem

    You need somehow to tell the system that the input is done.
    In your example, you say you want to enter '1'.
    You need to do something that tells the code, your input is finished, and that you don't want to type another '1' - maybe your want to enter '11'.
    So when you trigger that "end of input" event, you can connect a slot to it, and there put your logic.
    ==========================signature=============== ==================
    S.O.L.I.D principles (use them!):

    Do you write clean code? - if you are TDD'ing then maybe, if not, your not writing clean code.

  3. The following user says thank you to high_flyer for this useful post:

    zakachoka (9th May 2017)

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