Coding Concepts — If Else Conditionals — 30 Days Lost in Space Help Center

Make your Arduino make decisions. If/else statements let your code choose different actions based on sensor readings and button presses.

What are Conditionals?

Conditionals let your program make decisions. Based on whether a condition is true or false, different code runs.

Basic If Statement

if (temperature > 30) {
  Serial.println("It's hot!");
}

If/Else

if (buttonPressed) {
  digitalWrite(LED, HIGH);
} else {
  digitalWrite(LED, LOW);
}

If/Else If/Else

if (score >= 90) {
  Serial.println("A");
} else if (score >= 80) {
  Serial.println("B");
} else if (score >= 70) {
  Serial.println("C");
} else {
  Serial.println("F");
}

Comparison Operators

| Operator | Meaning | |----------|---------| | == | Equal to | | != | Not equal to | | < | Less than | | > | Greater than | | <= | Less than or equal | | >= | Greater than or equal |

Logical Operators

| Operator | Meaning | Example | |----------|---------|---------| | && | AND | if (a > 5 && b < 10) | | \|\| | OR | if (a > 5 \|\| b < 10) | | ! | NOT | if (!isLocked) |

Common Mistake

// WRONG: this is assignment, not comparison!
if (x = 5) { }

// CORRECT: comparison
if (x == 5) { }