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Thread: I Need Some Help With QObject::connect: No such signal QCommandLinkButton::click()

  1. #1
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    Default I Need Some Help With QObject::connect: No such signal QCommandLinkButton::click()

    hello everyone this is my first post here...
    i'am making a simple c++ program with gui,i'am building the gui manually using QCommandLinkButton and QLabel and QLineEdit,here's the code:

    numericalsystemsconverter.cpp:
    Qt Code:
    1. #include "numericalsystemsconverter.h"
    2. #include "ui_numericalsystemsconverter.h"
    3. #include <Qt>
    4. #include <QLabel>
    5. #include <QLineEdit>
    6. #include <QCommandLinkButton>
    7.  
    8. NumericalSystemsConverter::NumericalSystemsConverter(QWidget *parent) :
    9. QMainWindow(parent),
    10. ui(new Ui::NumericalSystemsConverter)
    11. {
    12. ui->setupUi(this);
    13.  
    14.  
    15. QLabel *title=new QLabel(this);
    16. title->setGeometry(0,0,400,30);
    17. title->setStyleSheet("font-size:20px;");
    18. title->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
    19. title->setText("Numerical Systems Converter");
    20.  
    21. QLineEdit *decimal_entry=new QLineEdit(this);
    22. decimal_entry->setGeometry(0,50,400,30);
    23. decimal_entry->setClearButtonEnabled(true);
    24. decimal_entry->setStyleSheet("font-size:20px;");
    25. decimal_entry->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
    26. decimal_entry->setPlaceholderText("Enter Your Decimal Number Here...");
    27.  
    28. QCommandLinkButton *dec2bin=new QCommandLinkButton(this);
    29. dec2bin->setGeometry(0,90,400,50);
    30. dec2bin->setStyleSheet("font-size:20px;");
    31. dec2bin->setText("Convert To Binary");
    32.  
    33. QLabel *result=new QLabel(this);
    34. result->setGeometry(0,250,400,30);
    35. result->setStyleSheet("font-size:20px;");
    36. result->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
    37. result->setText("The Result Should Appear Here...");
    38.  
    39. QObject::connect(dec2bin,SIGNAL(click()),result,SLOT(QLabel::setText("Hello World")));
    40. }
    41.  
    42. NumericalSystemsConverter::~NumericalSystemsConverter()
    43. {
    44. delete ui;
    45. }
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    whenever i compile this code the gui appears successfully,but in the Application Output i see this message:
    QObject::connect: No such signal QCommandLinkButton::click()
    how to solve this problem?

  2. #2
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    Default Re: I Need Some Help With QObject::connect: No such signal QCommandLinkButton::click(

    Hi, multiple problems here:
    1) the signal is called clicked(), not click()
    2) you cannot pass values inside the connect() call like the "Hello World" string. Also don't write QLabel::setText. Instead write only the name of the slot. The class is determined by the type of the receiving object, in this case "result".

    Best regards,

    Ginsengelf

  3. #3
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    Default Re: I Need Some Help With QObject::connect: No such signal QCommandLinkButton::click(

    Quote Originally Posted by Ginsengelf View Post
    Hi, multiple problems here:
    1) the signal is called clicked(), not click()
    2) you cannot pass values inside the connect() call like the "Hello World" string. Also don't write QLabel::setText. Instead write only the name of the slot. The class is determined by the type of the receiving object, in this case "result".

    Best regards,

    Ginsengelf

    thank you very much sir,i just want to understand the second part of your answer,can you give me an example?

  4. #4
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    Default Re: I Need Some Help With QObject::connect: No such signal QCommandLinkButton::click(

    Hi, something like this:
    Qt Code:
    1. {
    2. ....
    3. QObject::connect(dec2bin,SIGNAL(clicked()),this,SLOT(slotSetLabelText()));
    4. }
    5.  
    6. void NumericalSystemsConverter::slotSetLabelText()
    7. {
    8. result->setText("Hello World"); // this assumes result is a member of NumericalSystemsConverter
    9. }
    To copy to clipboard, switch view to plain text mode 

    Ginsengelf

  5. The following user says thank you to Ginsengelf for this useful post:

    Syrian Lucianos (23rd June 2017)

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