For Loop0%
For Loop
Beginner9 min read•Updated: 2026-09-03
For Loop
Python's for loop iterates directly over the items of any sequence or iterable.
Key Concepts & Detailed Explanation
The range() function:
- range(stop): 0 up to stop (exclusive).
- range(start, stop): start up to stop (exclusive).
- range(start, stop, step): increments by step.
Code Examples & Output
Python
# Iterating over range
print("Counting with range(1, 6):")
for i in range(1, 6):
print(i, end=" ")
print()
# Iterating over a list
languages = ["Python", "JavaScript", "Go"]
for lang in languages:
print(f"Programming in {lang}")
Expected Output:
Output
Counting with range(1, 6):
1 2 3 4 5
Programming in Python
Programming in JavaScript
Programming in Go
Best Practices & Common Pitfalls
Use range(len(my_list)) only if you strictly need index access; otherwise loop directly over items.
Practice Quiz
1. What does list(range(1, 5)) generate?
- A) [1, 2, 3, 4, 5]
- B) [1, 2, 3, 4]
- C) [0, 1, 2, 3, 4]
- D) [1, 5]
Answer: B
Explanation: The stop value (5) is exclusive, producing [1, 2, 3, 4].
2. How do you count backwards from 5 down to 1 using range?
- A) range(5, 0, -1)
- B) range(5, 1)
- C) range(1, 5).reverse()
- D) range(-5, -1)
Answer: A
Explanation: range(5, 0, -1) counts backwards with step -1.
Practice Challenge
Write a for loop that calculates the sum of all numbers from 1 to 100.
Next Lesson
Nested Loops
Continue learning with hands-on practice, examples, and exercises in the upcoming topic.
Related Lessons
| Previous Lesson | Next Lesson |
|---|---|
| While Loop | Nested Loops |
Practice Quiz
Test your understanding of this lesson with 1 questions. Each question has one correct answer.