beginner

For Loops

Master iteration with Python for loops to process collections and ranges.

Loops are essential for automating repetitive tasks in programming. The for loop in Python is elegant and powerful, allowing you to iterate over any sequence including lists, strings, and ranges. From processing data files to generating reports, for loops are used in virtually every Python application. This exercise teaches you to write efficient loops that make your code cleaner and more maintainable.

📚 Concepts & Theory

Basic For Loop:

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

for fruit in fruits:

    print(fruit)

Using range():

# 0 to 4

for i in range(5):

    print(i)

# 1 to 5

for i in range(1, 6):

    print(i)

# 0, 2, 4, 6, 8 (step of 2)

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

    print(i)

Looping with Index:

colors = ["red", "green", "blue"]

for index, color in enumerate(colors):

    print(f"{index}: {color}")

Loop Control:

break - Exit the loop immediately

continue - Skip to next iteration

for i in range(10):

    if i == 5:

        break  # Stop at 5

    if i % 2 == 0:

        continue  # Skip even numbers

    print(i)

Nested Loops:

for i in range(3):

    for j in range(3):

        print(f"({i}, {j})")

🎯 Your Challenge

Use a for loop with range() to calculate the sum of numbers from 1 to 10 (inclusive). Store the final sum in a variable called `total`.

📝 Starter Code

Python

# Calculate sum of 1 to 10
total = 0

# Your for loop here
for i in range(1, 11):
    # Add i to total

Initialize total to 0 before the loop
range(1, 11) gives numbers 1 through 10
Add each number to total inside the loop
Use total = total + i or total += i

Solution

Python

total = 0

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

# Alternative: total += i

Explanation

We initialize total to 0, then use range(1, 11) to generate numbers from 1 to 10 (11 is exclusive). Inside the loop, we add each number to total. After the loop completes, total contains the sum of all numbers (55). You can also use the shorthand += operator for addition.

⚠️ Common Mistakes to Avoid

Using range(10) instead of range(1, 11)
Forgetting that range end value is exclusive
Not initializing the sum variable before the loop
Wrong indentation inside the loop

❓ Frequently Asked Questions

The range() function's end value is exclusive, meaning it stops before reaching that number. To include 10, you must use 11 as the end value.

For loops are best when you know how many iterations you need. While loops are better when you want to loop until a condition becomes false.