Question

Just a simple program to add text to textedit when button is clicked…
anything wrong here??

#include<QPushButton>
#include<QApplication>
#include<QTextEdit>
#include<QWidget>
#include<QHBoxLayout>
#include<QLabel>

int main(int argc,char *argv[])
{
QApplication app(argc,argv);
QHBoxLayout *layout=new QHBoxLayout;
QTextEdit *text = new QTextEdit(); 
QWidget window;
QPushButton *button;

layout->addWidget(text);
button = new QPushButton();
button->setText(QChar(i+48));

QObject::connect(button,SIGNAL(clicked()),text,SLOT(setPlainText("hai")));

layout->addWidget(button);
window.setLayout(layout);
window.resize(500, 500);
window.show();

return app.exec();
}

Answer 1

You can’t use connect like that. You cannot pass parameters to the SLOT that are not present in the connected SIGNAL.

You will need to connect the clicked() signal to your own slot (with no argument), and call the setPlainText function yourself (or emit a new signal that has a QString parameter).

The other option is to use a QSignalMapper, as described in the Signals and Slots advanced usage section.