Object::connect: Parentheses expected, signal QAction::activated

Object::connect: Parentheses expected, signal QAction::activated

Object::connect: (receiver name: 'MainWindow')

这是提示你，语句中少了括号啊！

像这样：

 connect(print,SIGNAL(activated),this,SLOT(print()));

其实应该被写成：

 connect(print,SIGNAL(activated()),this,SLOT(print()));