Tutorial: Decisions & Loops

Programs become truly powerful when they can make choices on their own and repeat actions automatically.

In this tutorial, you’ll learn how to guide your code using if statements and repeat work using while loops.

Step 1: Making Decisions with if

An if statement tells your computer: “Only run this code if a specific condition is true.”

Let’s test if a player has reached a winning score:

score = 100

if score >= 100
    print "Congratulations, you won!"
end

Notice how clean the syntax is:

• No parentheses () required around score >= 100
• No colon : at the end of the line
• Just write your code, and close it with end

Step 2: Handling Alternatives with else and elseif

What if the condition isn’t met? You can provide a fallback response with else:

score = 45

if score >= 50
    print "You passed the test!"
else
    print "Keep practicing, you can do it!"
end

If you have multiple options to check (like assigning grades), chain them together using elseif:

score = 85

if score >= 90
    print "Grade: A"
elseif score >= 80
    print "Grade: B"
elseif score >= 70
    print "Grade: C"
else
    print "Grade: Needs improvement"
end

Pith checks each condition in order from top to bottom. As soon as one matches, it runs that code and moves on!

Step 3: Repeating Actions with while

What if you want to print a countdown or repeat an action 10 times? Instead of copying and pasting your code, use a while loop!

A while loop keeps running as long as its condition stays true:

# Remember: we use `mut` because `count` is going to change!
mut count = 1

while count <= 5
    print "Turn: " + count
    count = count + 1
end

print "All turns completed!"

Output:

Turn: 1
Turn: 2
Turn: 3
Turn: 4
Turn: 5
All turns completed!

Step 4: Special Loop Controls (break and continue)

Sometimes you want to break out of a loop early, or skip one specific round. Pith gives you two simple commands:

1. break: Stop the Loop Immediately

Use break when you’ve found what you were looking for and don’t need to keep searching:

mut number = 1

while number <= 10
    if number == 4
        print "Found number 4! Stopping early."
        break
    end
    print "Checking: " + number
    number = number + 1
end

Output:

Checking: 1
Checking: 2
Checking: 3
Found number 4! Stopping early.

2. continue: Skip to the Next Round

Use continue when you want to skip the rest of the current turn and jump straight to the next one:

mut number = 0

while number < 5
    number = number + 1
    if number == 3
        # Skip number 3!
        continue
    end
    print "Processing item: " + number
end

Output:

Processing item: 1
Processing item: 2
Processing item: 4
Processing item: 5

Notice that Processing item: 3 was skipped completely!

Next Steps

Now that you can guide your code’s decisions and repeat actions:

• Functions: Learn how to bundle your code into reusable actions
• Math & Logic: Combine conditions with and, or, and not