Pin arrays in Arduino

An array of pins turns repeated setup into a loop.

// An array of pins turns eight lines of setup into a loop.
const int STAGE_PINS[] = {3, 5, 6, 9};
const int STAGE_COUNT = 4;

void setup() {
  for (int i = 0; i < STAGE_COUNT; i++) {
    pinMode(STAGE_PINS[i], OUTPUT);
  }
}

void loop() {
  // Chase pattern: one stage light at a time.
  for (int i = 0; i < STAGE_COUNT; i++) {
    digitalWrite(STAGE_PINS[i], HIGH);
    delay(150);
    digitalWrite(STAGE_PINS[i], LOW);
  }
}

How it works

STAGE_PINS[] lists the outputs; one for sets them all up.
The chase loop indexes the array in order.
Adding a stage light is one number, not four lines.

Keywords and builtins used here

HIGH
LOW
OUTPUT
const
delay
digitalWrite
for
int
loop
pinMode
setup
void

The run, in numbers

Lines: 18
Characters to type: 402
Tokens: 105
Three-star pace: 65 tpm

At the three-star pace of 65 tokens a minute, this run takes about 97 seconds.

Type this snippet

Step 2 of 3 in Functions & state, step 17 of 27 in Language basics.

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