/*

  For Loop Iteration

  Demonstrates the use of a for() loop.

  Lights multiple LEDs in sequence, then in reverse.

  The circuit:

  - LEDs from pins 2 through 7 to ground

  created 2006

  by David A. Mellis

  modified 30 Aug 2011

  by Tom Igoe

  This example code is in the public domain.

  https://www.arduino.cc/built-in-examples/ForLoopIteration

*/

int timer = 35;           // The higher the number, the slower the timing.

void setup() {

  // use a for loop to initialize each pin as an output:

  for (int thisPin = 2; thisPin < 11; thisPin++) {

    pinMode(thisPin, OUTPUT);

  }
}

void loop() {

  // loop from the lowest pin to the highest:

  for (int thisPin = 2; thisPin < 11; thisPin++) {

    // turn the pin on:

    digitalWrite(thisPin, HIGH);

    delay(timer);

    // turn the pin off:

    digitalWrite(thisPin, LOW);

  }

  // loop from the highest pin to the lowest:

  for (int thisPin = 10; thisPin >= 2; thisPin--) {

    // turn the pin on:

    digitalWrite(thisPin, HIGH);

    delay(timer);

    // turn the pin off:

    digitalWrite(thisPin, LOW);

  }
}