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Loops: for loops (Part 1)

Following our exploration of Conditional Statements, this article introduces another fundamental concept in programming: loops. We'll start with the for loop, which allows you to iterate over a sequence of elements.

📚 Prerequisites​

A basic understanding of Python variables and data types, especially lists and strings.

🎯 Article Outline: What You'll Master​

In this article, you will learn:

  • ✅ What loops are and why they are useful.
  • ✅ The syntax of the for loop.
  • ✅ How to iterate over different types of sequences.
  • ✅ How to use the range() function with for loops.

🧠 Section 1: What are Loops?​

Loops are a way to execute a block of code multiple times. They are essential for automating repetitive tasks and for working with collections of data.

💻 Section 2: The for Loop​

The for loop in Python is used to iterate over a sequence (like a list, tuple, or string) or other iterable objects.

Syntax:

for item in sequence:
    # code to be executed for each item
  • item: A variable that takes on the value of the current item in the sequence during each iteration.
  • sequence: The collection of items to iterate over.

🛠️ Section 3: Iterating Over Different Sequences​

Let's look at some examples of how to use for loops with different types of sequences.

Iterating over a list:

fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

Iterating over a string:

for letter in "Python":
    print(letter)

🔬 Section 4: The range() Function​

The range() function is often used with for loops to generate a sequence of numbers.

range(stop):

for i in range(5):
    print(i) # Output: 0, 1, 2, 3, 4

range(start, stop):

for i in range(2, 5):
    print(i) # Output: 2, 3, 4

range(start, stop, step):

for i in range(0, 10, 2):
    print(i) # Output: 0, 2, 4, 6, 8

💡 Conclusion & Key Takeaways​

You've now learned the basics of the for loop, a powerful tool for iterating over sequences in Python.

Let's summarize the key takeaways:

  • Loops: A way to execute a block of code multiple times.
  • for Loop: Iterates over a sequence of elements.
  • range(): Generates a sequence of numbers, often used with for loops.

Challenge Yourself: Write a script that uses a for loop to print the numbers from 1 to 10, and then prints "Blastoff!".

➡️ Next Steps​

In the next article, we'll continue our exploration of loops with "Loops: for loops (Part 2)", where we'll cover nested loops and more advanced for loop patterns.

Happy coding!

Glossary (Python Terms)​

  • Loop: A control flow statement that allows code to be executed repeatedly.
  • Iteration: A single execution of the code block inside a loop.
  • Sequence: An ordered collection of items, such as a list, tuple, or string.

Further Reading (Python Resources)​