Output of Python program | Set 15 (Loops)

Prerequisite – Loops in Python
Predict the output of the following Python programs.

• 1) What is the output of the following program?

  x = ['ab', 'cd']
  for i in x:
      i.upper()
  print(x)

  Output:

  ['ab', 'cd']
  

  Explanation:
  The function upper() does not modify a string in place, but it returns a new string which here isn’t being stored anywhere. So we will get our original list as output.

• 2) What is the output of the following program?

  x = ['ab', 'cd']
  for i in x:
      x.append(i.upper())
  print(x)

  Output:

  No Output
  

  Explanation:
  The loop does not terminate as new elements are being added to the list in each iteration. So our program will stuck in infinite loop

• 3) What is the output of the following program?

  i = 1
  while True:
      if i%3 == 0:
          break
      print(i)
      i + = 1

  Output:

  No Output
  

  Explanation:
  The program will give no output as there is an error in the code. In python while using expression there shouldn’t be a space between + and = in +=.

• 4) What is the output of the following program?

  x = 123
  for i in x:
      print(i)

  Output:

  Error!
  

  Explanation:
  Objects of type int are not iterable instead a list, dictionary or a tuple should be used.

• 5) What is the output of the following program?

  for i in [1, 2, 3, 4][::-1]:
      print (i)

  Output:

  4
  3
  2
  1
  

  Explanation:
  Adding [::-1] beside your list reverses the list. So output will be the elements of original list but in reverse order.

This article is contributed by Avinash Kumar Singh. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.