float Dist;
Vector3 pos1, pos2;
pos1 = Commands->Get_Position(obj1);
pos2 = Commands->Get_Position(obj2);
Dist = Commands->Get_Distance(pos1, pos2);
if(Dist <= 40.0f){ // If the distance is less than 40 metres
	// do something
}
else{ // Distance is greater than 40 metres
	// do nothing?
}

float Dist = Commands->Get_Distance(Commands->Get_Position(obj1),Commands->Get_Position(obj2));
if(Dist <= 40.0f){ // If the distance is less than 40 metres
	// do something
}
else{ // Distance is greater than 40 metres
	// do nothing?
}

if((Commands->Get_Distance(Commands->Get_Position(obj1),Commands->Get_Position(obj2))) <= 40.0f){ // If the distance is less than 40 metres
	// do something
}

Vector3 pos1, pos2;
pos1 = Commands->Get_Position(obj1);
pos2 = Commands->Get_Position(obj2);

Vector3 gap = pos1 - pos2; //Doesn't matter which order the subtraction is in.
float dist = gap.length(); //Where length() returns the magnitude of the vector (is this in the sdk?)

class Vector3
{
public:
    float x, y, z;

    float length()
    {
        return sqrt(x*x + y*y + z*z);
    }
}

float Get_Distance ( GameObject* obj1, GameObject* obj2 )
{
	// Gets distance between two objects
	return Commands->Get_Distance ( Commands->Get_Position ( obj1 ), Commands->Get_Position ( obj2 ) );
}

float Get_Distance ( GameObject* obj, Vector3 pos )
{
	// Gets distance object and position
	return Commands->Get_Distance ( Commands->Get_Position ( obj ), pos );
}