For Loops

Basic For Loop

  1. # iterate over range
  2. for i in range(5):
  3.     print(i)
  4. #ans: 0
  5. #ans: 1
  6. #ans: 2
  7. #ans: 3
  8. #ans: 4

Range with Start/Stop

  1. # range(start, stop)
  2. for i in range(2, 7):
  3.     print(i)
  4. #ans: 2, 3, 4, 5, 6

Range with Step

  1. # range(start, stop, step)
  2. for i in range(0, 10, 2):
  3.     print(i)
  4. #ans: 0, 2, 4, 6, 8

Iterate Over List

  1. # iterate list items
  2. fruits = ["apple", "banana", "cherry"]
  3. for fruit in fruits:
  4.     print(fruit)
  5. #ans: apple
  6. #ans: banana
  7. #ans: cherry

Iterate with Index

  1. # enumerate for index and value
  2. fruits = ["apple", "banana"]
  3. for i, fruit in enumerate(fruits):
  4.     print(i, fruit)
  5. #ans: 0 apple
  6. #ans: 1 banana

Iterate String

  1. # iterate over characters
  2. for char in "abc":
  3.     print(char)
  4. #ans: a
  5. #ans: b
  6. #ans: c

Exercises - Part 1

  1. # how many iterations?
  2. for i in range(10):
  3.     pass
  4. #ans: 10 iterations

Exercises - Part 2

  1. # what is i after loop?
  2. for i in range(3):
  3.     pass
  4. #ans: i is 2 (last value)

Exercises - Part 3

  1. # what prints?
  2. for i in range(3, 3):
  3.     print(i)
  4. #ans: nothing (empty range)

Exercises - Part 4

  1. # negative step?
  2. for i in range(5, 0, -1):
  3.     print(i)
  4. #ans: 5, 4, 3, 2, 1

Exercises - Part 5

  1. # what is sum?
  2. total = 0
  3. for i in range(1, 6):
  4.     total += i
  5. #ans: 15 (1+2+3+4+5)

Exercises - Part 6

  1. # enumerate start?
  2. for i, x in enumerate(['a', 'b'], start=1):
  3.     print(i)
  4. #ans: 1, 2

Exercises - Part 7

  1. # what is final i?
  2. for i in range(5):
  3.     if i == 3:
  4.         pass
  5. #ans: i is 4 (loop continues)

Exercises - Part 8

  1. # nested loop count?
  2. count = 0
  3. for i in range(3):
  4.     for j in range(2):
  5.         count += 1
  6. #ans: count is 6

Exercises - Part 9

  1. # empty list?
  2. for item in []:
  3.     print(item)
  4. #ans: nothing (empty list)

Exercises - Part 10

  1. # what prints?
  2. for i in range(1, 10, 3):
  3.     print(i)
  4. #ans: 1, 4, 7

Exercises - Part 11

  1. # modify loop variable?
  2. for i in range(3):
  3.     i = 10
  4.     print(i)
  5. #ans: 10, 10, 10 (but doesn't affect iteration)

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