How can I make sense of the `else` clause of Python loops?

by

An if statement runs its else clause if its condition evaluates to false.
Identically, a while loop runs the else clause if its condition evaluates to false.

This rule matches the behavior you described:

  • In normal execution, the while loop repeatedly runs until the condition evaluates to false, and therefore naturally exiting the loop runs the else clause.
  • When you execute a break statement, you exit out of the loop without evaluating the condition, so the condition cannot evaluate to false and you never run the else clause.
  • When you execute a continue statement, you evaluate the condition again, and do exactly what you normally would at the beginning of a loop iteration.
    So, if the condition is true, you keep looping, but if it is false you run the else clause.
  • Other methods of exiting the loop, such as return, do not evaluate the condition and therefore do not run the else clause.

for loops behave the same way. Just consider the condition as true if the iterator has more elements, or false otherwise.

More Related Contents:

  1. Python: How to keep repeating a program until a specific input is obtained? [duplicate]
  2. Converting for loops to while loops in python
  3. Using a loop to create and assign multiple variables (Python) [duplicate]
  4. for or while loop to do something n times [duplicate]
  5. Can someone explain what all the codes mean? PYTHON [closed]
  6. Why doesn’t this python code run infinite times? [closed]
  7. One line recursive loop in python
  8. How to do for loop through all items of a list except the first [duplicate]
  9. How to check if all elements of a list match a condition?
  10. Is it possible to implement a Python for range loop without an iterator variable?
  11. How do I loop through a list by twos? [duplicate]
  12. Pythonic way to combine for-loop and if-statement
  13. Are infinite for loops possible in Python? [duplicate]
  14. Why does a for-loop with pop-method (or del statement) not iterate over all list elements [duplicate]
  15. Python nested looping Idiom
  16. Understanding for loops in Python
  17. How to increment variable names/Is this a bad idea [duplicate]
  18. Is it possible to make a `for` loop without an iterator variable? (How can I make make code loop a set number of times?)
  19. Mixing files and loops
  20. Modifying a list while iterating when programming with python [duplicate]
  21. Skip over a value in the range function in python
  22. Assignment Condition in Python While Loop
  23. Strange result when removing item from a list while iterating over it in Python
  24. in a while loop, where should you place a variable for counting?
  25. How to loop through all but the last item of a list?
  26. for loops and iterating through lists
  27. “for loop” with two variables? [duplicate]
  28. Why do I get “List index out of range” when trying to add consecutive numbers in a list using “for i in list”? [duplicate]
  29. Why does this python dictionary get created out of order using setdefault()?
  30. List append() in for loop raises exception: ‘NoneType’ object has no attribute ‘append’ [duplicate]

Leave a Comment