CODEWITHSUNDEEP
c++qt
Alex D Rex
Alex D Rex

Reputation: 89

cannot call the function in child from the parent

I am developing a game using C++ in Qt creator.

I can call the fuctions of the child class in main without an issue, but when I try to call a function in child class from my parent class, the program unexpectedly closes.

I have declared all the public attributes in the .h file of the parent class. T tried removing those attributes and placing them inside the .h file of the child class, then it works fine. But W want to keep them in the parent class and access those from the child class.

Please help get this to work, I tried several times but I could not figure it out.

.h file of parent class:

class Game:public QGraphicsView,public home{

Q_OBJECT

public:

Game(QWidget* parent=0);

virtual ~Game(){}

void createBlockCol(double x);
void creatBlockGrid();
virtual void setbackground();

QPushButton *btn2;
QPushButton *btn3;
QPushButton *btn4;
QGraphicsScene* scene;
QGraphicsScene *scene2;
QGraphicsView* view;
QPushButton *btn;
QPushButton *btn1;
QGraphicsProxyWidget *pr;
QGraphicsProxyWidget *pr1;


QGraphicsProxyWidget *pr2;
QGraphicsProxyWidget *pr3;
QGraphicsProxyWidget *pr4;
QGraphicsPixmapItem* item1;
QGraphicsPixmapItem* item;

private slots:
void start();

This is .cpp class of parent

Game::Game(QWidget *parent): QGraphicsView(parent){
scene = new QGraphicsScene(0,0,466,600);
setScene(scene);

}

void Game::setbackground(){

scene2 = new QGraphicsScene(0,0,400,600);
QGraphicsView* view = new QGraphicsView(scene2);
item = new QGraphicsPixmapItem(QPixmap(":/Ies/uu.jpg"));
scene2->addItem(item);
view->show();
game_function *gm; //call a function in child class
gm->set_buttons();
}

child class .h file

class game_function:public Game
{
Q_OBJECT

public:

void set_background();
void mainwindow();
void set_buttons();


private slots:
void button_help();
};

.cpp file

void game_function::set_buttons(){



btn = new QPushButton;
QObject::connect(btn,SIGNAL(clicked()),this,SLOT(startgame()));
btn->setStyleSheet("background-color: white");
pr = this->scene2->addWidget(button);
btn->setAutoFillBackground(true);
btn->setIcon(QIcon(":/Ies/main.png"));
btn->setIconSize(QSize(131,41));
pr->setPos(130,430);

btn1 = new QPushButton;
QObject::connect(btn1,SIGNAL(clicked()),this,SLOT(stopgame()));
btn1->setStyleSheet("background-color: white");
pro = this->scene2->addWidget(button1);
btn1->setAutoFillBackground(true);
btn1->setIcon(QIcon(":/Images/exit.png"));
btn1->setIconSize(QSize(131,41));
pr->setPos(130,500);

Upvotes: 0

Views: 457

Answers (1)

2785528
2785528

Reputation: 5566

is there ay way i can call this function

You might not be too far from trying a polymorphic invocation ...

perhaps if you

A) add "Game::set_buttons()", and make it virtual, perhaps pure virtual, somewhere in class header:

class Game:public QGraphicsView,public home{
// ... perhaps after

virtual ~Game(){}

virtual void setbuttons() = 0;

// ...
} // end of class Game

then, in method "Game::setbackground()" you can use it ... replace this

// undefined behavior - gm not initialized
//game_function *gm; //call a function in child class
//gm->set_buttons();

with

this->set_buttons();

Upvotes: 2

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