If you don't want to reset the crab modules to 0* each match, you would need to add an index to the encoder (limit switch, reflective tape, etc) to know your absolute angle. Or you could check out one of these
US Digital Absolute Kit Encoders. These mount the same way as the KOP encoder, but let you read absolute rotation (0-360*) on an analog input pin.
To remember variables across methods in your code, just declare the object globally in the class.
Code:
class YourRobot : public SimpleRobot{
Encoder *crab;
YourRobot(void){
crab = new Encoder(1,2);
}
}