Where to find good explanation re Manipulating Strings/char[]

I am new to Arduino, with a 21 year lay-off since I last programmed at all, but I want to create an engine monitoring system on my boat to display, log and alarm e.g. oil pressure, water temperature, battery state etc. and Arduino seems to be the perfect vehicle.

In order to display the information, I need to output to LCD, and to a host computer - probably a Raspberry Pi, messages such as "Oil P 3.9 Mbar", along with date time and alarm indications.

I think I am no idiot, having programmed micros to mainframes in many different languages, but I am really struggling to find information to help me build these messages. I have picked up that char is more reliable than Strings, but then get really confused when the Strings reference page starts:
char Str1[15];
char Str2[8} = {'a', 'r'.....}; etc.

and I cannot find anyway of concatenating the elements or stuffing a buffer without incurring the wrath of the compiler.

Any suggestions where to find a good explanation of char[], Strings, char *, and associated library/standard language functions to manipulate them? Before the Internet you bought a decent language reference book and that was it!

waljoh:
I cannot find anyway of concatenating the elements

https://www.google.com/search?q=strncat

waljoh:
stuffing a buffer

https://www.google.com/search?q=snprintf

(floating-point is not supported)

you can find most (or all) of string manipulation here:

I use cplusplus as my reference for string functions

...R

Thanks for the pointers, J

Also, in the non-verbose category: Standard C library for AVR-GCC.