Python Loops Tutorial

Welcome to the Python Loops Tutorial by SimplyLearn. In this session, we covered the fundamentals of loops in Python, focusing on different types of loops and their applications.

Agenda

• Basics of loops
• For loops in Python
• While loops in Python
• Nested loops in Python

For Loops

• Definition: For loops iterate over items in a sequence (list, tuple, dictionary, string).
• Syntax:

  for iterator_variable in sequence:
      # statements
  

• Flow Chart:
  • Iterate through each item in a sequence.
  • Execute statements until the end of the sequence.

Examples of For Loops

• Iterating over a string:

  s = "simply learn"
  for i in s:
      print(i)
  

  • Prints each character in the string.

• Using the end parameter in print:

  • Change end character using end parameter.

  for i in s:
      print(i, end="*")
  

• Iterating over a list:

  programming = ["Java", "Python", "Ruby", "HTML"]
  for iter in programming:
      print(iter)
  

  • Prints each item in the list.

• Finding the average of numbers:

  list_num = [20, 25, 10, 50, 45]
  sum = 0
  for i in list_num:
      sum += i
  average = sum / len(list_num)
  

• Using range() function:

  for i in range(1, 10):
      print(i)
  

  • Iterates from 1 to 9.

  • With step:

  for i in range(0, 10, 2):
      print(i)
  

  • Prints numbers with a step of 2.

• Nested For Loops:

  companies = ["Google", "Apple", "PWC", "Uber"]
  for i in companies:
      for letter in i:
          print(letter)
  

• For loop with else clause:

  for i in range(0, 10, 3):
      print(i)
  else:
      print("The loop has completed execution")
  

• Using break and continue:

  • break: Exit the loop before completing all iterations.
  • continue: Skip the current iteration and move to the next.

While Loops

• Definition: Executes a set of statements as long as a condition is true.
• Syntax:

  while expression:
      # statements
  

Examples of While Loops

• Basic While Loop:

  i = 0
  while i < 10:
      i += 1
      print(i)
  

• Using break and continue:

  • Break out of the loop using break.
  • Skip to next iteration using continue.

• Using else with While Loop:

  i = 1
  while i < 5:
      print(i)
      i += 1
  else:
      print("i is not less than 5")
  

• List operations using While Loop:

  a = [1, 2, 3, 4, 5]
  while a:
      print(a.pop())
  

  • Pops elements from the list.

Nested Loops

• Definition: A loop inside another loop.
• Types:
  • For loop inside a for loop.
  • While loop inside a while loop.
  • Combination of for and while loops.

Examples of Nested Loops

• Printing patterns:

  for i in range(11):
      for j in range(i):
          print("*", end=" ")
      print()
  

  • Prints a right-angled triangle pattern.

• Multiplying elements of two lists:

  list1 = [2, 4, 6]
  list2 = [2, 4, 6]
  for i in list1:
      for j in list2:
          if i == j:
              continue
          print(i, "*", j, "=", i * j)
  

• Checking perfect numbers:

  a = 1
  while a <= 100:
      sum = 0
      for i in range(1, a):
          if a % i == 0:
              sum += i
      if sum == a:
          print("Perfect number:", a)
      a += 1
  

• Perfect number between 1 and 100 are 6 and 28.

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These loops help in iterating over data structures in Python to perform repeated tasks efficiently. Understanding loops is crucial for writing efficient and effective Python code.