First... why would you not simply use the defines you show in your header...

Code:
// instead of...
x = getsensaddr(5);

//use...
x = SENSOR_5;
I have a pretty strong notion that's why the defines are there...

If you need those addresses in variables create an array...
Code:
// add to header
const int Sensor[6] = {SENSOR_1, SENSOR_2, SENSOR_3, SENSOR_4, SENSOR_5, SENSOR_6};

// use as...
int i = 4;
x = Sensor[i];