Cannot call function without object

Hi. I've got a problem. I have public member function called clear() which looks like this:

Code:

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void MainWindow::clear()
            {
              tableWidget->clear();
              tableWidget_2->clear();
              tableWidget_3->clear();
              tableWidget_4->clear();
              tableWidget_5->clear();
              tableWidget_6->clear();
              tableWidget_7->clear(); 
             }

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and when I call it in another member function

Code:

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MainWindow::clear()

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There appear error that I can't call member function MainWindow::clear() without object. What's the problem about? Regards

You need something like this:

Code:

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this->clear();

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or simply call clear().

The class resolution operator ( :: ) is used when calling static functions.

But usually, when you're using other member functions, you can just call them. Using "this" is a well known ( some say bad ) Java practice.

Regards

I tried to use only call() but there appear error that clear() is not declared

Quote:

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Originally Posted by Salazaar

I tried to use only call() but there appear error that clear() is not declared

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Where do you want to invoke MainWindow::clear() (i.e. in what method or function)?

Quote:

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Originally Posted by marcel

Using "this" is a well known ( some say bad ) Java practice.

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Not only Java, but Python and PHP too. It's completely unnecessary and makes your code look ugly, but I wonder whether I could have any positive outcomes.

If the clear function is within QMainWindow why not put the following in your QMainWindow header file :

Code:

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extern MainWindow *theApp;

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and then in your .cpp file for MainWindow, someplace at the top :

Code:

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MainWindow *theApp;   // I'm presuming MainWindow derives from QMainWindow...

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and in your constructor :

Code:

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theApp = this;

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This way, you can make calls to the clear function from other classes by :

Code:

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theApp->clear();

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as long as you include the MainWindow header file...

Regards,
Steve