6.1 Iterations loops

6.1a What are Python loops?

Python loops are constructs that allow you to execute a block of code repeatedly, based on a condition or a sequence. They are fundamental to programming because they help you avoid redundant code, making your programs more efficient and easier to manage.

There are two main types of loops in Python: for-in loops and while loops. As we will see in section 6.4, the while loop can also be paired with an else block.

6.1b Why do we need loops?

• Repetition - Loops allow you to repeat a block of code multiple times without having to write it out repeatedly.

  • Example: Printing numbers 1 to 100 without writing 100 print statements.

• Efficiency - Loops make your code more efficient and easier to read and maintain.

  • Example: Iterating through a list of items to perform the same operation on each item.

• Automation - Automate repetitive tasks.

  • Example: Processing each file in a directory, or fetching data from a list of URLs.

• Dynamic Code Execution - Loops can handle dynamic inputs and data structures that may vary in size.

  • Example: Processing user input until they decide to quit.