Key Concepts

Review core concepts you need to learn to master this subject

break Keyword

Python List Comprehension

Python For Loop

The Python continue Keyword

Python for Loops

Python Loops with range().

Infinite Loop

Python while Loops

See more

break Keyword

numbers = [0, 254, 2, -1, 3]

for num in numbers:
  if (num < 0):
    print("Negative number detected!")
    break
  print(num)
  
# 0
# 254
# 2
# Negative number detected!

In a loop, the break keyword escapes the loop, regardless of the iteration number. Once break executes, the program will continue to execute after the loop.

In this example, the output would be:

  • 0
  • 254
  • 2
  • Negative number detected!
Loops
Lesson 1 of 2
  1. 1
    Introduction
    Suppose we want to print() each item from a list of dog_breeds. We would need to use the following code snippet: dog_breeds = [‘french_bulldog’, ‘dalmatian’, ‘shihtzu’, ‘poodle’, ‘collie’] print(…
    Start
  2. 2
    Create a For Loop
    In the previous exercise, we saw that we can print each item in a list using a for loop. A for loop lets us perform an action on each item in a list. Using each element of a list is known as _i…
    Start
  3. 3
    Using Range in Loops
    Previously, we iterated through an existing list. Often we won’t be iterating through a specific list, we’ll just want to do a certain action multiple times. For example, if we wanted to print out…
    Start
  4. 4
    Infinite Loops
    We’ve iterated through lists that have a discrete beginning and end. However, let’s consider this example: my_favorite_numbers = [4, 8, 15, 16, 42] for number in my_favorite_numbers: my_favorit…
    Start
  5. 5
    Break
    We often want to use a for loop to search through a list for some value: items_on_sale = [“blue_shirt”, “striped_socks”, “knit_dress”, “red_headband”, “dinosaur_onesie”] # we want to check if the…
    Start
  6. 6
    Continue
    When we’re iterating through lists, we may want to skip some values. Let’s say we want to print out all of the numbers in a list, unless they’re negative. We can use continue to move to the next i …
    Start
  7. 7
    While Loops
    We now have seen and used a lot of examples of for loops. There is another type of loop we can also use, called a while loop. The while loop performs a set of code until some condition is reach…
    Start
  8. 8
    Nested Loops
    We have seen how we can go through the elements of a list. What if we have a list made up of multiple lists? How can we loop through all of the individual elements? Suppose we are in charge of a …
    Start
  9. 9
    List Comprehensions
    Let’s say we have scraped a certain website and gotten these words: words = [“@coolguy35”, “#nofilter”, “@kewldawg54”, “reply”, “timestamp”, “@matchamom”, “follow”, “#updog”] We want to make a…
    Start
  10. 10
    More List Comprehensions
    Let’s say we’re working with the usernames list from the last exercise: >>> print(usernames) [“@coolguy35”, “@kewldawg54”, “@matchamom”] We want to create a new list with the string “ please fol…
    Start
  11. 11
    Review
    Good job! In this lesson, you learned - how to write a for loop - how to use range in a loop - what infinite loops are and how to avoid them - how to skip values in a loop - how to write a while l…
    Start

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