Python for Loop

In the last lesson, we learned about the Python Ternary Operator. Now let’s repeat the same job without writing the same code again and again.

🧩 Let’s Talk About Repetition

Imagine we have to write “Hello” on a whiteboard 100 times.

Would we write it 100 times by hand? That would take forever. And our hand would hurt.

No. We would find a way to do it faster. Maybe we use a stamp. Or we print it. Or we get a machine to do it.

Computers are great at repetition. They never get tired. They never get bored. They can do the same thing a million times without complaining.

That is what loops are for.

🔧 What Is a Loop in Python?

A loop is a way to repeat something.

Instead of writing the same code again and again, we write it once. And we tell Python: “Do this 10 times” or “Do this for each item in this list.”

Python has two main types of loops:

• for loop — repeat a specific number of times, or for each item in a collection
• while loop — repeat as long as a condition is true

In this article, we will learn about the for loop.

💡 What Is a Python for Loop?

A for loop goes through a sequence of items. One by one. And for each item, it does something.

Think of it like this. We have a list of names. We want to say hello to each person.

We could write:

print("Hello, Alex")
print("Hello, Sam")
print("Hello, John")

But what if we have 100 names? That is a lot of lines.

With a for loop, we write it once.

names = ["Alex", "Sam", "John"]

for name in names:
    print(f"Hello, {name}")

Hello, Alex
Hello, Sam
Hello, John

See? The loop goes through each name. And for each one, it prints a greeting.

That is the power of for.

🧪 The Structure of a Python for Loop

for variable in sequence:
    # do something

• for — the keyword that starts the loop
• variable — a name we choose. It holds the current item.
• in — the keyword that connects the variable to the sequence
• sequence — the thing we want to loop through
• : — the colon
• Then indented code — what to do for each item

The indented code runs once for each item in the sequence.

🔁 Using range() in Python for Loop

The most common way to loop a specific number of times is with range().

for i in range(5):
    print(i)

0
1
2
3
4

Wait. Why does it start at 0? And why does it stop at 4?

Because range(5) gives us numbers from 0 to 4. Not including 5.

That is a bit weird at first. But it is how Python works. The end number is not included.

Let me show us.

for i in range(3):
    print("Hello")

Hello
Hello
Hello

It ran 3 times. Because range(3) gives 0, 1, 2. That is 3 numbers.

So range(n) runs the loop n times.

⚙️ range() with Start and End

We can also give range() a start and end.

for i in range(2, 6):
    print(i)

2
3
4
5

It starts at 2. And goes up to but not including 6.

So range(2, 6) gives 2, 3, 4, 5.

🔍 range() with Step

We can also give it a step. The step is how much to increase each time.

for i in range(0, 10, 2):
    print(i)

0
2
4
6
8

It starts at 0. Goes up to 10 (not including). And jumps by 2 each time.

We can also go backwards.

for i in range(5, 0, -1):
    print(i)

5
4
3
2
1

It starts at 5. Goes down to 0 (not including). And steps by -1 each time.

🧭 Looping Through a String in Python

We can loop through a string. Each character is an item.

for letter in "Python":
    print(letter)

P
y
t
h
o
n

See? It goes through each character one by one.

📋 Looping Through a List in Python

We can loop through a list. Each item is an item.

fruits = ["apple", "banana", "orange"]

for fruit in fruits:
    print(fruit)

apple
banana
orange

🎯 Python for Loop: A Real-Life Example

Let’s calculate the sum of numbers from 1 to 10.

total = 0

for i in range(1, 11):
    total += i

print(f"Sum: {total}")

Sum: 55

Let me explain what happened.

• total starts at 0.
• The loop goes from 1 to 10.
• Each time, it adds the current number to total.
• After the loop, total is 55.

That is a common pattern. We start with something. And we update it in the loop.

📚 Another Example — Multiplication Table

number = 7

for i in range(1, 11):
    print(f"{number} x {i} = {number * i}")

7 x 1 = 7
7 x 2 = 14
7 x 3 = 21
7 x 4 = 28
7 x 5 = 35
7 x 6 = 42
7 x 7 = 49
7 x 8 = 56
7 x 9 = 63
7 x 10 = 70

That is a multiplication table. And we wrote it with just three lines.

✅ The Loop Variable in Python for Loop

The variable in the for loop is just a name. We can call it anything.

for i in range(3):
    print(i)

for x in range(3):
    print(x)

for num in range(3):
    print(num)

All three do the same thing. The name does not matter.

But it is good to use a meaningful name. For numbers, i is common. For items, use the item name.

for fruit in fruits:
    print(fruit)

That is clearer than:

for x in fruits:
    print(x)

⚠️ Common Mistakes with Python for Loop

❌ Mistake 1: Forgetting the Colon

Here is a mistake we all make. We write the for line and forget the colon.

for i in range(5)
    print(i)

Error! Missing colon.

So what do we do? We add the colon.

for i in range(5):
    print(i)

🚫 Mistake 2: Forgetting Indentation

for i in range(5):
print(i)

Error! The print needs indentation.

So what do we do? We indent the code inside the loop.

for i in range(5):
    print(i)

🛑 Mistake 3: Using the Wrong Variable

for i in range(5):
    print(x)   # Error! x is not defined

The loop variable is i. So we use i. Not x.

So what do we do? We use the correct variable name.

for i in range(5):
    print(i)

🐞 Mistake 4: Thinking range(5) Gives 1 to 5

for i in range(5):
    print(i)

This gives 0 to 4. Not 1 to 5.

If we want 1 to 5, we use:

for i in range(1, 6):
    print(i)

Next, we will learn about the Python while Loop, which repeats code while a condition remains true.