Python for Dummies Pt.4: Loops

In the last post, we figured out how to shove all your data into a List so it isn't scattered all over your script. But if you have a list of 100 things and want to print every single one, writing print(list[0]), print(list[1]), print(list[2]) is a miserable way to spend your afternoon.

Computers are incredibly dumb, but they are very fast. Loops are how we force the computer to do the repetitive, boring work for us.

---

1. The for Loop (The List Consumer)

A for loop goes through a list, one item at a time, and does whatever you tell it to do with that item. It doesn't complain. It doesn't ask for a break.

games = ["Minecraft", "Roblox", "Elden Ring"]

# "game" is just a temporary variable name we made up for the current item
for game in games:
    print(f"Booting up {game}...")
    
print("All games loaded. Try not to rage quit.")

What it actually does: Python looks at the list, grabs "Minecraft", runs the code block. Then it grabs "Roblox", runs the code block. It keeps going until the list is empty.

---

2. The range() Function (Doing things X amount of times)

Sometimes you don't have a list. You just want to annoy someone by doing the exact same thing 5 times in a row. That’s where range() comes in.

# Remember, Python starts counting at 0. 
# So range(5) will count: 0, 1, 2, 3, 4.

for i in range(5):
    print(f"Warning #{i}: Shariq, clean your room.")

If you don't use loops for this kind of stuff, you are basically just using a thousand-dollar machine as a typewriter.

---

3. The while Loop (The "Are we there yet?" loop)

A for loop stops when it reaches the end of a list or a range. A while loop is more stubborn. It will keep running its code block over and over again until a specific condition becomes False.

player_hp = 3

while player_hp > 0:
    print(f"You have {player_hp} HP. You take a hit!")
    # Subtract 1 from HP every time the loop runs
    player_hp = player_hp - 1 

print("You have 0 HP. Game Over.")

CRITICAL RULE: If you forget to actually change the condition inside a while loop (like forgetting to subtract the HP), the loop will literally run forever until your computer runs out of memory and crashes. This is called an infinite loop, and yes, you will accidentally write one eventually.

---

The Cheat Sheet

Loop Type	When to actually use it
for loop	When you know exactly how many times you want to run the code (like going through a list of 5 items).
while loop	When you don't know how long it will take, but you know when it should stop (like waiting for a player's health to hit 0).

Now you know how to automate your code. Next time, we’ll look at If/Else Statements, which is how we actually teach the computer to make a decision instead of just blindly running whatever we type.