connect(btn, SIGNAL(clicked()), this, SLOT(slot_lolo()) );double Класс::result(){ return spin1->value()*spin2->value() - 2.3;}void Класс::slot_lolo(){ textedit->setText(QString::number(result()));}
connect (ThermodynamicRunButton, SIGNAL(clicked()), this, SLOT(my_function());
double a;void my_function(){ a=0;}