Choosing with if and else

Part of the First Circuits section of Coddy's Arduino journey. Lesson 19 of 22.

else gives an if a second path, for when the condition is false:

if (count > 3) {
  Serial.println("big");
} else {
  Serial.println("small");
}

Exactly one of the two runs. The board checks the condition, takes one path, and carries on after the last brace.

With a counter, if and else let a sketch behave one way at first and another way later: count grows each time round loop(), and once it passes a number, the condition flips.

Challenge

Medium

Red LED on pin 8, green LED on pin 9. Make red blink five times, then green take over:

at the top, make int count = 0;
at the start of loop(), add 1 to count
if count is more than 5, blink green once (500 ms on, 500 ms off)
else, blink red once

Press Run, then Check.

Try it yourself

int count = 0;

void setup() {
  pinMode(8, OUTPUT);  // red
  pinMode(9, OUTPUT);  // green
}

void loop() {
  // add 1 to count

  // if count is more than 5, blink green, else blink red
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in First Circuits

1Hello, Board

Blink an LED Setup and Loop Change the Blink Speed An LED of Your Own Two LEDs Taking Turns Comments in Your Sketch

4Decisions

Decisions with ifChoosing with if and elseComparing Values Combining Conditions Read a Button

2Talking to Your Computer

Hello, Serial Monitor Print Versus Println Printing Numbers Your First Variable Counting Up When an Int Runs Out

3Math on the Board

Named Constants Arithmetic Operators Integer Division Decimals with float A Blink That Speeds Up

Practice on your own: Arduino playground