I’d need a simple template of a code that would read an ATAT-formatted structure, parse some command line arguments, etc.
Have a look at the file
atat/src/skelread.c++
It’s a demonstration code that shows you the a "skeleton" of an ATAT-like command.
The atat/src/makefile file also contains the make rule under item "skelread:"
You can just type
make skelread