for Loops

Iteration over … Something

Iteration: a central concept everywhere

  • Programs build and manipulate data

  • … and occasionally (most often?) iterate over data

  • ⟶ Specialized looping construct: for

for name in ['Caro', 'Johanna', 'Eva', 'Jörg']:
  • name: loop variable

  • Bound to the current element in the list, four times in a row

  • A list is iterable - many other types participate in this game

break, continue, else

Just as with while: usual looping features

  • break ends the loop - else clause not executed

  • continue executes block with next element (if any)

haystack = ['straw', 'mouse', 'straw', 'needle', 'straw']
for item in haystack:
    if item == 'needle':
    print("couldn't find needle")