【QT】error: 'SIGNAL' was not declared in this scope

error: 'SIGNAL' was not declared in this scope  未在此范围内声明。

connect(ui->Btnshowhello,SIGNAL(clicked(bool),this,SLOT(BtnshowhelloSlot()));

 

 

其他错误导致的此报错。。

是SIGNAL后括号忘了。