[Proj] Problem understanding the new API

[Matthias Gabriel]

Hi,

I've been using the old proj4 API successfully an did understand that by 
specifying source and target systems i could transform my coordinates. 
Now I tried to use the new API (proj.h) which seems to be much cleaner 
and easier to use. I checked the manual and found:

"the fundamental concept of transformations in PROJ are now handled in a 
single transformation object (PJ) and not by stating the source and 
destination systems as previously."

Ok, fine.. understood. Unfortunately my problem definition is still the 
same: given a set of coordinates in source system A I want to calculate 
their representation in system B. ..

So before it was straight-forward: I specified what I had and what I 
wanted, but now I don't know how to get the required "direct 
transformation" from A to B using the new API?! I tried to use a 
cs2cs-style string with the "+to" specifier  but that didn't work. 
proj_create_crs_to_crs would be an option but doesn't quite suit my 
problem (we don't use EPSG codes etm).

Could you please give me a hint on how to proceed here?

Best Regards,
Matthias