Overview
🧭 Overview of Loops in Python
In Python, loops allow you to execute a block of code repeatedly. The two main types are for-loops and while-loops. Knowing which loop to choose depends on the task and whether you know how many repetitions are needed.
🔁 For-Loops
A for-loop is used when you know beforehand how many times the loop should run, usually based on an iterable like a list, tuple, string, or a range of numbers.
Common Use Cases
- Running a fixed number of repetitions with
range() - Iterating over a list or string
🔄 While-Loops
A while-loop runs as long as a specified condition is true. It’s useful when you don’t know how many iterations you’ll need.
Common Use Cases
- Waiting for user input
- Looping until a stop condition is met
- Reading data until the end of a file
🔍 Comparison Table
| Feature | For-Loop | While-Loop |
|---|---|---|
| Repetition Count | Known | Unknown |
| Control Variable | Automatic via iterable | Manually updated |
| Best For | Lists, ranges, sequences | Conditions that evolve over time |
| Risk | Low – typically ends naturally | High – may run forever if not stopped |
| Exit Strategy | Automatic at end of iterable | Manual condition must become False |
⚠️ Important: With while-loops, the risk of an infinite loop is higher if you forget to update the condition. Always make sure the loop has a clear exit strategy!
✅ Tips for Using Loops
- Always make sure your
whileloop has a clear exit condition. - When using
for, consider whether you need the index (for i in range(len(list))) or just the value (for item in list). - Use
breakto exit a loop early, andcontinueto skip to the next iteration.