Issue with Dynamically Created Widgets
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I've declared a member array to store the pointers for a bunch of Qt Control widgets (QLineEdit),
In the main code, I programmatically create these widgets and assign, however they are only accessible while the function is in scope:
// MyGui.h class myGui : public QMainWindow, private Ui::uiFormWin { Q_OBJECT public: MyGui(QMainWindow *parent = 0); Test(); private: QTimer *pUiTimer; QLineEdit* le2T[ 32 ]; public slots: void GuiUpdate(void); } // MyGui.c MyGui::MyGui(QMainWindow *parent) : QMainWindow(parent) { // Create Objects and Assign for ( int i = 0 ; i < 32; i++ ){ le2T[ i ] = new QLineEdit (this); } // This Displays fine: le2T [ 0 ]->setText ("Hello"); // Setup Timer To Update Line Edit Later pUiTimer = new QTimer(this); pUiTimer->setInterval(100); connect(pUiTimer, SIGNAL(timeout()), this, SLOT(GuiUpdate()) ); } void MyGui::GuiUpdate( void ) { // This next line causes Run-Time Crash -- le2T[0] object is null! le2T [ 0 ]->setText ("World"); // Error }Interestingly, even though they are no longer accessible, they still appear on the GUI.
I've tried making these QLineEdit objects as members variables in my class (instead of an array of pointers), but, accessing QLineEdit's member functions fails.. and Qt doesn't even auto-detect these as QLineEdit objects!
.h QLineEdit le2T[ 32 ]; .cpp le2T[ 0 ].setText ("World"); // ErrorHow can I create an array of widgets at run-time, and save as member variables so that they can be accessed from any method in the class?
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Hello,
In general there is no problem to create widgets on the stack, or in the heap. It should work either way.One thing that catches my eye is that you're not initializing your form (not calling
setupUi), although this shouldn't be a problem. Otherwise your code looks correct. I still don't see how you start you timer, maybe you could provide some more code, so we are able to provide further assistance?One additional thing to check:
Are you sure that the arrayle2Tis NULL, and not thethispointer? You might be trying to dereference a nullthis, that'd lead to the crash. Try stopping the debugger just after enteringGuiUpdatebefore actually modifying the line edit array and make sure that you have an object you're operating on.Kind regards.
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I've declared a member array to store the pointers for a bunch of Qt Control widgets (QLineEdit),
In the main code, I programmatically create these widgets and assign, however they are only accessible while the function is in scope:
// MyGui.h class myGui : public QMainWindow, private Ui::uiFormWin { Q_OBJECT public: MyGui(QMainWindow *parent = 0); Test(); private: QTimer *pUiTimer; QLineEdit* le2T[ 32 ]; public slots: void GuiUpdate(void); } // MyGui.c MyGui::MyGui(QMainWindow *parent) : QMainWindow(parent) { // Create Objects and Assign for ( int i = 0 ; i < 32; i++ ){ le2T[ i ] = new QLineEdit (this); } // This Displays fine: le2T [ 0 ]->setText ("Hello"); // Setup Timer To Update Line Edit Later pUiTimer = new QTimer(this); pUiTimer->setInterval(100); connect(pUiTimer, SIGNAL(timeout()), this, SLOT(GuiUpdate()) ); } void MyGui::GuiUpdate( void ) { // This next line causes Run-Time Crash -- le2T[0] object is null! le2T [ 0 ]->setText ("World"); // Error }Interestingly, even though they are no longer accessible, they still appear on the GUI.
I've tried making these QLineEdit objects as members variables in my class (instead of an array of pointers), but, accessing QLineEdit's member functions fails.. and Qt doesn't even auto-detect these as QLineEdit objects!
.h QLineEdit le2T[ 32 ]; .cpp le2T[ 0 ].setText ("World"); // ErrorHow can I create an array of widgets at run-time, and save as member variables so that they can be accessed from any method in the class?
