Preprocessor to repeat statements - arduino

Question

I've just started working with Arduino. I seem to write code like this often:
int input_pins[] = {6, 3, 8, 2};
int input_state[4];
void setup() {
}
void loop() {
for (int i = 0; i < 4; i++){
input_state[i] = digitalRead(input_pins[i]);
}
}
Is there a preprocessor (or something like it) to produce the following effective code?
int input_state[4];
void setup() {
}
void loop() {
input_state[0] = digitalRead(6);
input_state[1] = digitalRead(3);
input_state[2] = digitalRead(8);
input_state[3] = digitalRead(2);
}

Answer 1

Arduino programming has C++ underneath, why do you want to use something as limited as preprocessing?
If you start out with the following code:
///////////////////////////////////////
class DigitalRead
{
public:
DigitalRead(int pins[]);
int operator[](const int index);
int len;
int *mypins;
};
DigitalRead::DigitalRead(int pins[])
{
mypins = pins;
for(len = 0; pins[len] != -1; len++) {};
}
int DigitalRead::operator[](const int index)
{
if (index > len) return -1;
return digitalRead(mypins[index]);
}
///////////////////////////////////////
int pins[] = {6, 3, 8, 2, -1};
DigitalRead input_state = DigitalRead(pins);
void setup()
{
}
void loop()
{
// print the state of pin 6, change as needed
Serial.println(input_state[0]);
}
you can improve on things (setting the pins for input in DigitalRead::DigitalRead e.g.)j. Once things work move the stuff between /////// lines into a library.