can program X run on laptop and talk to program Y on MEGA 2560?

I am a retired mainframe CICS programmer.
I have decided to order an ARDUINO MEGA 2560.
But first I am studying basic electronics for a few weeks.
I look forward to learning C.
I don't have a C compiler on my laptop.
I have downloaded ARDUINO IDE.
As I understand it, I will code a C program on my PC, ARDUINO IDE will compile it, I will upload the program to MEGA 2560, and it will run on MEGA 2560.
In addition to my program running on MEGA 2560,
is it possible to create another C program to run on my laptop only
so that it can talk to my C program running on MEGA 2560?

is it possible to create another C program to run on my laptop only
so that it can talk to my C program running on MEGA 2560?

Yes but not with the arduino IDE. You need some other compiler for your PC.

The arduino is C++ not C.

The Processing language is free and often used to write programs on the PC that talk to the arduino. That is Java, which is C with knobs on.

I do the same with the same MEGA 2560 too.
The Arduino IDE contains a C-compiler with it's own standard library.
You should be able to program it vias USB to serial port or the serial port to serial port.
I was writing a python based server which is communicating with my Arduino-Firmware over usb to serial port and it is working well.

Any PC programming language that can send and receive bytes via the serial port can communicate with an Arduino. All of the common languages can.

...R

OK, thank you very much.
The world of PCs is awesomely different from the old IBM mainframes.
For consistency and a flatter learning curve,
I presume it would be best to get a C++ compiler on my PC
just for those programs that would run on PC only.
My PC 2 gig netbook has WINDOWS 7 STARTER.
Where could I get a free download of a C++ compiler that does NOT assume that I know all the nuances of navigating through each downloading decision point that probably seem trivial and insignificant to all the PC geeks & wizards?

The world of PCs is awesomely different from the old IBM mainframes.

I think you misspelled “infinitely better”.

There are a lot of C/C++ compilers around, and they are usually integrated with IDE's such as Code::Blocks, Eclipse, Netbeans, and many more...