API for Automation HAT?

I wish to do programming in C for Automation HAT.
I wounder if there is an API for Automation HAT?
If any where can I find a description of the API?

We don’t have a C library for Automation HAT, only Python, but if you’re wanting to do GPIO access in C then WiringPi may be what you need: http://wiringpi.com/

You’ll need a C library for the ADS1015: https://cdn-shop.adafruit.com/datasheets/ads1015.pdf
And the SN3218: https://github.com/pimoroni/sn3218/blob/master/datasheets/sn3218-datasheet.pdf

But neither of these devices are particularly challenging and wiringPi contains code to drive them both, albeit the ADC code is for the ads1115 and the SN3218 code may be buried in the PiGlow device library, but they’re there for reference.