Hi Stefan,
Thanks for your detailed reply.
As I am building a scientific calculator as a project to entertain myself, the requirement is for as much precision as I can get with no restrictions on the number range to be used.
My requirement is to convert a double float into a char array so I can display it on a 16 digit display. The display I have chosen requires a char array. I have been surprised that I have not been able to find a C++ function that supports this requirement in the Arduino environment.
I have looked at the Adafruit library source code after UKHeliBob's replies.
The printFloat() function only works with 7 segment displays and not the 14 segment. (I tested it this morning).
I will take your advice and write a sketch just to test the display functionality, as posting all of the 450 lines here would not be productive. Then I can post it here.
Gordon.