📏 Python range() Function — Generating Number Sequences Easily

Introduction 🌟

The range() function is used to generate a sequence of numbers. It is most commonly used inside for loops, but can also be converted into lists, iterated manually, or used in logic conditions.

Note

💡 range() does NOT create a list in memory — it creates a lightweight sequence object, making it memory efficient.

1. Basic Syntax 🧱

range(stop)range(start, stop)range(start, stop, step)

2. range(stop) — Starts From 0 🔢

range_stop.py

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

✔️ Outputs: 0, 1, 2, 3, 4
✔️ Stops before 5

3. range(start, stop) — Custom Start 📍

range_start_stop.py

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

✔️ Outputs: 2, 3, 4, 5
✔️ Stop value is *exclusive*

4. range(start, stop, step) — With Step Size 🚶‍♂️

range_step.py

for i in range(1, 10, 2):
    print(i)

✔️ Outputs odd numbers: 1, 3, 5, 7, 9

5. Negative Step — Counting Backwards ⬇️

range_negative_step.py

for i in range(10, 0, -1):
    print(i)

✔️ Countdown from 10 to 1
✔️ Stop value (0) is excluded

6. Converting Range to List 📚

range_to_list.py

nums = list(range(1, 6))
print(nums)  # [1, 2, 3, 4, 5]

Note

✔️ Useful when you need all values stored at once.

7. Using Range in While Loop 🔄

range_in_while.py

i = 0
nums = range(5)

while i < len(nums):
    print(nums[i])
    i += 1

8. Range With Conditions 🧠

range_condition.py

for i in range(1, 20):
    if i % 5 == 0:
        print(i)

✔️ Prints multiples of 5 between 1 and 19.

9. Using Range in Nested Loops 🪜

nested_range.py

for i in range(1, 4):
    for j in range(1, 4):
        print(i, j)

10. Skipping Values With Step 🏃‍♂️

skip_values.py

for i in range(0, 20, 3):
    print(i)

✔️ Outputs: 0, 3, 6, 9, 12, 15, 18

11. Using Range for Indexing 📌

indexing_with_range.py

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

for i in range(len(fruits)):
    print(i, fruits[i])

12. range() in Reverse Using reversed() 🔄

range_reversed.py

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

13. Check If Value Exists in Range 🔍

range_membership.py

print(5 in range(1, 10))   # True
print(10 in range(1, 10))  # False

14. Range Efficiency 🚀

range() is extremely efficient because it generates values on demand rather than storing them in memory.

Note

🧠 Use range() for large sequences to avoid memory issues.

15. Real-World Example 🌍

real_world_example.py

for attempt in range(1, 4):
    pin = input("Enter PIN: ")
    if pin == "1234":
        print("Access granted")
        break
    print("Wrong PIN, attempt", attempt)

Conclusion 🎉

>>“range() is the backbone of Python loops — simple, powerful, and memory efficient.” ✨

You now fully understand the range() function in Python! Want the next topic? Try Pass Statement, Functions, Parameters, or List Comprehensions. Just tell me! 😊