Welcome to Python loops! Loops are essential programming constructs that help us automate repetitive tasks. Instead of writing the same code over and over, loops allow us to execute code repeatedly. This flowchart shows the basic loop structure: we start, check a condition, execute code if true, and repeat until the condition becomes false. Python provides two main types of loops: for loops that iterate over sequences, and while loops that repeat based on conditions.
Now let's explore for loops in detail. A for loop iterates over sequences like lists, strings, or ranges. The syntax starts with the 'for' keyword, followed by a variable name, then 'in', then the iterable, and finally a colon. The indented code block executes for each item. Let's see this in action with a simple example that processes a list of numbers, showing how the loop variable changes with each iteration.
While loops operate differently from for loops. Instead of iterating over a sequence, while loops continue executing as long as a condition remains true. This makes them more flexible for situations where you don't know how many iterations you need. However, you must be careful to update the loop variable to avoid infinite loops. Let's compare equivalent for and while loops with a countdown example, showing how the condition is evaluated before each iteration.
Loop control statements give you precise control over loop execution. The break statement immediately exits the loop, useful for early termination when a condition is met. The continue statement skips the rest of the current iteration and moves to the next one, perfect for filtering. The else clause is a lesser-known feature that executes only when the loop completes normally without encountering a break. These control statements make loops more flexible and efficient for handling complex logic.