c++ - Change label text from another class using Qt signals and slots -

i'm trying change text of class label class. have class mainwindow, contains label.

i have bot class wanna change value of label.

i'm trying create signal , slots have no idea start.

i created signal , slots so:

//in mainwindow.h signals: void changetextsignal();  private slots: void changetext();  //in mainwindow.cpp void mainwindow::changetext(){ this->label->settext("foobar"); } 

but have no idea how connect signal able change label's text class.

read on qt signal-slot mechanism. if understand correctly, trying signal bot mainwindow label text needs change. here's how it...

//bot.h class bot {     q_object;     //other stuff here signals:     void textchanged(qstring); public:     void somefunctionthatchangestext(const qstring& newtext)     {         emit textchanged(newtext);     } }  //mainwindow.cpp mainwindow::mainwindow {     //do other stuff     this->label = new qlabel("original text");     mybot = new bot;   //mybot bot* member of mainwindow in example     connect(mybot, signal(textchanged(qstring)), this->label, slot(settext(qstring))); }  void mainwindow::hello() {     mybot->somefunctionthatchangestext("hello world!"); }