← All lessons/Conditionals· Lesson 11 of 32

if / else

Use else and else-if chains to choose between two or more options.

About 7 min

Plan B with else

An if runs code when its condition is true. Add an else block and you also handle the case when it's false. Exactly one of the two blocks runs:

if (condition) {
  // runs when true
} else {
  // runs when false
}
One path or the other, never both.

Choosing between many options

Chain else if to test several conditions in order. p5 checks them top to bottom and runs the first one that's true:

A score of 85 lands in the middle branch, painting gold.

TIP

Order matters: put the most specific or highest conditions first, since the first true branch wins and the rest are skipped.

Your turn

A variable hour is set to 20. Write an if / else: if hour < 18, call background(135, 206, 235) for a daytime sky; otherwise (else), call background(20, 20, 60) for a night sky. Since hour is 20, the night branch should run.

Hints