STEAM Miniature Model Building and Prototyping in Semarang

1. Introduction: What Are Loops?

Loops repeat an action automatically. Instead of writing 30 separate print() statements, write the instruction once and tell Python how many times to run it.

2. Why and Where We Use Loops

• Automating repetitive output
• Iterating over collections and strings
• Controlling start/stop boundaries
• Searching data element-by-element

3. The Basic range() Loop

for i in range(3):
    print("Python is fun")

Runs three times (i = 0, 1, 2).

4. Iterating Over a String

word = "Python"
for char in word:
    print(char)

Each character prints on its own line because each print() starts a new line.

5. Patterns with Loops

rows = 5
for i in range(rows):
    spaces = " " * (rows - i - 1)
    stars = "*" * (2 * i + 1)
    print(spaces + stars)

Builds a centered pyramid of asterisks.