C++ What is and isn't implemented in the Arduino IDE

That all sounds perfectly reasonable and I am well aware of the physical limitations.

AVR-gcc implementation of the compiler and library ? It sounds as though I should know what that is and I suspect that it is only the tip of the iceberg.

Clearly the terminology I used isn't correct, what I need to know is what is available in a standard Arduino IDE, irrespective of how it got there, that comes later.
I am sure that if I went looking for C++ solutions on Google I would find loads of solutions many of which don't work/arn't implemented in the Arduino IDE.

I am more than happy to do the research and reading but I don't know what to look for to get me started.
In fact I am far more concerned about asking silly questions that I could have answered by doing a bit of reading.

sprintf ... in other places, I was a little confused I think I have used it in php

Thanks for the link and the pointer to look into libs, that will be easier now I have an idea where to look
I am really green at this, I only just discovered that I can look at a library file in the IDE, they don't format well in notepad ... Oops

Cheers
Al