qt-connection

问题 I am beginner to qt. I was working on calculator gui application, I have already defined slots like numPressed() when any of the number pushbutton is pressed on the calculator that will be displayed on the lineEdit. void Calculator::numPressed(){ QPushButton *button = (QPushButton *)sender(); QString buttonValue = button->text(); Qstring display = ui->lineEdit->text(); Qdouble ProcessedValue = previousValue + buttonValue.toDouble(); . . . ui->lineEdit->setText(QString::number(ProcessedValue))

问题 I am beginner to qt. I was working on calculator gui application, I have already defined slots like numPressed() when any of the number pushbutton is pressed on the calculator that will be displayed on the lineEdit. void Calculator::numPressed(){ QPushButton *button = (QPushButton *)sender(); QString buttonValue = button->text(); Qstring display = ui->lineEdit->text(); Qdouble ProcessedValue = previousValue + buttonValue.toDouble(); . . . ui->lineEdit->setText(QString::number(ProcessedValue))

问题 I am beginner to qt. I was working on calculator gui application, I have already defined slots like numPressed() when any of the number pushbutton is pressed on the calculator that will be displayed on the lineEdit. void Calculator::numPressed(){ QPushButton *button = (QPushButton *)sender(); QString buttonValue = button->text(); Qstring display = ui->lineEdit->text(); Qdouble ProcessedValue = previousValue + buttonValue.toDouble(); . . . ui->lineEdit->setText(QString::number(ProcessedValue))

问题 I repeatedly see people having problems with slots not being called. I would like to collect some of the most common reasons. So maybe I can help people and avoid a lot of redundant questions. What are reasons for signal / slot connections not working? How can such problems be avoided? 回答1: There are some rules that make life with signals and slots easier and cover the most common reason for defective connections. If I forgot something please tell me. 1) Check the debug console output: When