Loop Control Statements

In the previous articles, we've explored both the for loop and the while loop, understanding how they iterate through code. In this article, we'll learn loop control statements which allow us to tailor the behavior of loops to suit our specific needs.

There are three main loop control statements in Python: break, continue, and pass.

break: Terminates the loop prematurely.

continue: Skips the rest of the current iteration and continues with the next one.

pass: The pass statement is used as a placeholder in Python to avoid syntactical errors.

Using break to Exit a Loop

Use break when you want to exit a loop prematurely based on a certain condition.

Example

You are searching for a specific item in a list, and once you find it, you can exit the loop immediately.

In this example, we used an if statement to search for the number 4 within the list. As the loop iterates through the numbers, the break statement is used to exit the loop immediately upon finding the number 4. Consequently, only the numbers 1, 2, and 3 are printed before the break statement exits the loop. Early exit from a loop is an optimization strategy that saves computational resources and reduces the loop's execution time.

Using continue to Skip an Iteration

Use continue when you want to skip the rest of the current iteration and move to the next iteration of the loop.

Example

You are processing a list of numbers, and you only want to print odd numbers and skip even numebrs.

In this example, we utilize a for loop to iterate through a list of numbers. We employ an if statement with the condition num % 2 == 0 to identify even numbers. When num is even, the continue statement skips the remaining code, here it's the print(num). It allows the loop to advance to the next iteration. Conversely, when num is odd and fails to meet the if condition, print(num) executes to print odd numbers.

Use pass as a Placeholder

Use pass as a placeholder if you need a loop structure with no immediate code inside, either for temporary holding or future implementation.

The pass statement isn't limited to loops; it's also applicable in functions, classes, and other structures where a syntactical placeholder is required.

Example

Defining a loop structure intended for later development.

This code iterates through the numbers list, but it doesn't contain any meaningful code within the loop. To prevent Python from raising an error due to an empty loop body, the pass statement is used as a placeholder, allowing the loop to remain syntactically valid.