combining two projects into one

Projects General Guidance
1

So I bought one of those robotic cars that come with a few different projects to make. One is a car that follows lines (lets call it mode 1) and another is a car that avoids obstacles (mode 2). I made both projects and learned lots about coding. I would like to combine both projects just so I dont have to reupload the code to switch between "modes".
I have an IR that can be used to switch between modes.
What would be the correct way of doing this? I think I can figure out the code if I know the correct procedure. I'm still a novice though.

2

Put the two things in functions, then implement a basic state machine. So you get something like this:

#define LINEFOLLOWER 0
#define OBSTACLEAVOIDANCE 1
byte mode = LINEFOLLOWER;
void loop() {
  checkIR();
  switch (mode) {
    case LINEFOLLOWER:
      linefollower();
      break;

    case OBSTACLEAVOIDANCE:
      obstacleavoidance();
      break;
  }
}

void checkIR() {
  // Read command over IR.
  // set mode accordingly.
  if (command == 'l') mode = LINEFOLLOWER;
  if (command == 'o') mode = OBSTACLEAVOIDANCE;
}

void linefollower() {
  // original linefollower loop()
}
void obstacleavoidance() {
  // original obstacleavoidance loop()
}
3

Hi, Here's an example using IR to control a robot car:

http://arduino-info.wikispaces.com/RobotKitMenu-9

And some suggestions on combining sketches:

http://arduino-info.wikispaces.com/CombiningArduinoSketches