How to use QT to control pins and signals in Linuxcnc via shared memory?

1.Now I have a signal called qqq
u@u-desktop:~$ sudo halcmd show sig qqq
Signals:
Type          Value  Name     (linked to)
bit           FALSE  qqq

2.The signal changes when I execute the following code in QT
halcmdsets("qqq","1");

3.The value of the signal is now true
u@u-desktop:~$ sudo halcmd show sig qqq
Signals:
Type          Value  Name     (linked to)
bit            TRUE  qqq

Finally, how should I write the halcmdsets? My English level is relatively poor, please forgive me for the improper description.
 

In the C++ language I use in QT, I want to change both the signal and the pin. I looked at the files in LinuxCNC and found the hal_lib.c file, which can help me realize the idea of changing signal values and pin values in QT. But now I have this idea but I don't know how to implement it using QT.

Ok, I will analyze the file halModulo. c, may I ask whether I can contact you through any chat software? I would like to continue to consult you about this aspect.

Why do you need this signal? And how did you create it. (Python / C++) Maybe you need to attach to an already existing one. and hang it on the button.

how to use hal with qt
This is old, but gives you info.