Loops

  • For loops are useful for executing a command over a large number of items.
  • You can create a for loop like so:
for letter in 'abc':
    print(letter.upper())

Output:

A
B
C

  • The name after for (e.g. letter) is just a variable name
  • You can loop over dictionary keys:
phone_numbers = {"John Smith":"+37682929928","Marry Simpons":"+423998200919"}
for value in phone_numbers.keys():
    print(value)

Output:

John Smith
Marry Simpsons

  • You can loop over dictionary values:
phone_numbers = {"John Smith":"+37682929928","Marry Simpons":"+423998200919"}
for value in phone_numbers.values():    print(value)

Output:

+37682929928
+423998200919

  • You can loop over dictionary items:
    1. phone_numbers = {“John Smith”:”+37682929928″,”Marry Simpons”:”+423998200919″}
    2. for key, value in phone_numbers.items():
    3. print(key, value)
    Output: ('John Smith', '+37682929928')('Marry Simpons', '+423998200919')
  • While loops will run as long as a condition is true:
    1. while datetime.datetime.now() < datetime.datetime(2090, 8, 20, 19, 30, 20):
    2. print(“It’s not yet 19:30:20 of 2090.8.20”)
    The loop above will print out the string inside print() over and over again until the 20th of August, 2090.