We are going to create a Rubik's cube solver. We have approached the programming aspect of this problem by using the language we are most comfortable with, C. We are programming the algorithm to solve the cube in C using Notepad++. At this point, we are trying to figure out how we can use the Arduino Mega, with a some stepper motors and connect them to our C program or get the Arduino IDE to communicate and take commands from our program which is written in Notepad++. Could someone guide us on how we should be doing this? Thanks for your help!
Have a look at the examples in Serial Input Basics - simple reliable ways to receive data. There is also a parse example to illustrate how to extract numbers from the received text.
The technique in the 3rd example will be the most reliable.
You can send data in a compatible format with code like this (or the equivalent in any other programming language)
Serial.print('<'); // start marker Serial.print(value1); Serial.print(','); // comma separator Serial.print(value2); Serial.println('>'); // end marker
If you need more help please explain what parts of the task will be done on your PC, what parts will be done by the Arduino and what data needs to pass between the two.
Have a look at Processing for the PC program.
Is the C program going to run on the computer, or the Arduino board?