const int analogPin = A0;
const int ledCount = 10;

int ledPins[] = {
  2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};

float floatMap(float x, float in_min, float in_max, float out_min, float out_max) {
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

void setup() {
  // loop over the pin array and set them all to output:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT);
  }

  Serial.begin(9600);
}

void loop() {
  // read the potentiometer:
  int sensorReading = analogRead(analogPin);
  // map the result to a range from 0 to the number of LEDs:
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

  // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    // if the array element's index is less than ledLevel,
    // turn the pin for this element on:
    if (thisLed < ledLevel) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    // turn off all pins higher than the ledLevel:
    else {
      digitalWrite(ledPins[thisLed], LOW);
    }
  }

  float voltage = floatMap(sensorReading, 0, 1023, 0, 5);

  // print out the value you read:
  Serial.print("Analog: ");
  Serial.print(sensorReading);
  Serial.print(", Voltage: ");
  Serial.println(voltage);
  delay(50);
}