QT tutorial: signal and slot mechanism

One 、 Connection of signal and slot
1、QT5 Writing above version ：
connect（xxx,&yyy,this,&zzz）;
xxx： Sender of signal , This parameter is a pointer
&yyy： Signaler , An internal signal （ Format ：& + The name of the signaler class + ：： + Signal name ）, To add an address symbol
this： The receiver of the signal , This parameter is also a pointer （ Is not necessarily this）
&zzz： Signal processing function , To add an address symbol , It belongs to this,

2、QT edition 5 The following is a way to write ：
connect（xxx,SIGNAL（yyy（））,this,SLOT（zzz（）））;
xxx： Sender of signal , This parameter is a pointer
yyy（）： Signaler
this： The receiver of the signal , This parameter is also a pointer （ Is not necessarily this）
zzz（）： Signal processing function , It belongs to this,

Two 、 Custom slot function
1、 Slot function in Qt5, It can be any class member function 、 Global function 、 Static functions 、lambda expression （ Implicit functions ）
2、 The slot function needs to correspond to the signal （ Return value 、 Parameters ）
for example ：
void mysignal（int ,double,QString）;// The signal
void myslot（int ,double,QString）;// Slot function
3、 The signal has no return value , The return value of the slot function ：void
4、 The parameters of the slot function are to receive the data transmitted by the signal
5、 The parameters of the slot function should not be greater than the number of parameters of the signal , The parameters of the slot function can be less than the number of parameters of the signal
6、 Slot functions can be overloaded
7、 stay “private slots：” Make a statement or “public slots：” Make a statement

3、 ... and 、 Custom signal
1、 Must be in “signals：” Make a statement
2、 There can be parameters
3、 Overloading can happen
4、 The return value is Void
5、 Sending signal ：emit+ Signal name

Four 、hide（） function
It means to hide the current window

5、 ... and 、static
Static value , for example static int i = 0; It means static Zheng Xingzhi i, It will not be rebuilt later i=0, Instead, keep the last value