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.