Coding PID Controller in QSpice using Discrete formula

Hello everyone,
I continued the idea of creating a PID controller in QSpice using Discrete formula (specifically using Tustin method / Trapezoid method) and wrote a code to run it. But again, I had trouble with my code because to be honest, I’m quite weak in coding C/C++ so I really need your help!
Could you please check it out and find what wrong with my code?
Thank you very much, for thousand times!!!
I’m very appreciated of all your support!