How to pass a string to a function on a connect signal

[jins]

Hi am trying pass a string to a function that searches a database, as soon as a user types in the lineedit.

I am watching the linedit for any text change then want to send text in the lineedit to a function called searchfunc.

What am i missing or doing wrong.

connect(ui->lineEdit, SIGNAL(textChanged(QString)), ,SLOT(searchfunc(QString)));

connect(ui->lineEdit, SIGNAL(textChanged(QString)), ,SLOT(searchfunc(QString)));

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[wysota]

Most likely you are missing the third argument to connect(). At least the snippet you pasted here is missing it.

[jins]

Most likely you are missing the third argument to connect(). At least the snippet you pasted here is missing it.

Yes you are correct, but i am little confused to what i should omplement there as i just want to pass a simple string to a function, all teh examples i have seen on the web are not showing this.

[BalaQT]

hi,

but i am little confused to what i should omplement there

just put this pointer in the third arg

connect(ui->lineEdit, SIGNAL(textChanged(QString)),this,SLOT(searchfunc(QString)));

connect(ui->lineEdit, SIGNAL(textChanged(QString)),this,SLOT(searchfunc(QString)));

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hope it helps

Bala

[jins]

hi,


just put this pointer in the third arg

connect(ui->lineEdit, SIGNAL(textChanged(QString)),this,SLOT(searchfunc(QString)));

connect(ui->lineEdit, SIGNAL(textChanged(QString)),this,SLOT(searchfunc(QString)));

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hope it helps

Bala

Hi Bala

Thank you very much for replying. I tried that before and i am still get same error for the connect code.

"expected constructor, destructor or type conversion before ' ( ' token"

[FelixB]

maybe you forgot the Q_OBJECT macro? is searchfunc" defined as a slot?

[jins]

maybe you forgot the Q_OBJECT macro? is searchfunc" defined as a slot?

Hi FelixB

This is what i have in the mainwindow.h file

private slots:
    void searchfunc(QString searchtext);

private slots:
    void searchfunc(QString searchtext);

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[BalaQT]

hi @jins ,

as FelixB said, did u forget the Q_OBJECT macro.

class myclass : public QWidget
{
  Q_OBJECT
   private slots:  
      void searchfunc(QString searchtext);
}

class myclass : public QWidget
{
  Q_OBJECT
   private slots:  
      void searchfunc(QString searchtext);
}

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did u include #include <QtGui>

pls check

pls post the class part
Bala

[jins]

hi @jins ,

as FelixB said, did u forget the Q_OBJECT macro.

class myclass : public QWidget
{
  Q_OBJECT
   private slots:  
      void searchfunc(QString searchtext);
}

class myclass : public QWidget
{
  Q_OBJECT
   private slots:  
      void searchfunc(QString searchtext);
}

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PLS CHECK

Bala

I have the QObject specified already, I am sorry i didnt paste the entire code before here it is:

class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private:
    Ui::MainWindow *ui;
 
    DB* dbManager;
    bool opendb;
    QList<PersonData*> persondata;
 
private slots:
    void searchfunc(QString searchtext);

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;

    DB* dbManager;
    bool opendb;
    QList<PersonData*> persondata;

private slots:
    void searchfunc(QString searchtext);

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[BalaQT]

did u include #include <QtGui>

Bala

[jins]

Hi Bala

I have #include <QtGui/QApplication > in main.cpp but just in case i have also added #include <QtGui> and i am still getting the error message.

[BalaQT]

hi,
how u r compiling?
try qmake-qt4

clean all the files, delete all the obj files and then try qmake-qt4


shall i know where u r using connect?
pls post the connect block

Bala

[jins]

Ok i will like to publically apoligise for my stupidity, i had cut and pasted the connect line outside MainWindow::MainWindow setup and didnt realise. I am so sorry for wasting your time but also very greatful for all your help and advice (BalaQT the third argument you advised worked a dream)

[BalaQT]

Ok i will like to publically apoligise for my stupidity, i had cut and pasted the connect line outside MainWindow::MainWindow setup and didnt realise. I am so sorry for wasting your time but also very greatful for all your help and advice (BalaQT the third argument you advised worked a dream)

hi jins,
its nice the problem is solved
all the best for ur work.
Bala