[SIZE="6"]a simple question:error lnk2019 unresolved external symbol[/SIZE]

I define a class A as follows:

Code:

---

class A
{
     protected:
     void contentsMousePressEvent (QMouseEvent *e);
     signals:
     void extractClicked();
}
void A::contentsMousePressEvent (QMouseEvent *e)
{
  .....
  emit extractClicked();
}

---

when compile,error:error LNK2019: unresolved external symbol ...
means that can not find the function extractClicked.
Why?

Quote:

---

Originally Posted by weixj2003ld

I define a class A as follows:

Code:

---

class A
{
     protected:
     void contentsMousePressEvent (QMouseEvent *e);
     signals:
     void extractClicked();
}
void A::contentsMousePressEvent (QMouseEvent *e)
{
  .....
  emit extractClicked();
}

---

when compile,error:error LNK2019: unresolved external symbol ...
means that can not find the function extractClicked.
Why?

---

Try this:

Code:

---

class A:public QWidget
{
 Q_OBJECT
 
     protected:
     void contentsMousePressEvent (QMouseEvent *e);
     signals:
     void extractClicked();
}

---