Python for and while Loops with basic Examples

This is the basic ppt for 1st practical or lecture for Python loops.

1. Python Loops for loops While loops f or loops A for loop is used for iterating over a sequence (that is either a list, a tuple , a dictionary, a set, or a string ). Iterating means Repetitive execution of the same block of code over and over. With the for loop we can execute a set of statements, once for each item in a list, tuple , set etc. Prof. Kartiki Deshmukh

2. Example fruits = ["apple", "banana", “mango"] for x in fruits:   print(x) Output: apple banana mango Prof. Kartiki Deshmukh

3. Looping Through a String S trings are iterable objects, they contains a sequence of characters. Prof. Kartiki Deshmukh

4. Example for x in  “mango":   print(x ) Output : m a n g o Prof. Kartiki Deshmukh

5. The break Statement With the break statement we can stop the loop before it has looped through all the items. Prof. Kartiki Deshmukh

6. Example fruits = ["apple", "banana", "cherry"] for x in fruits:   print(x)   if x == "banana":      break Output: apple banana Prof. Kartiki Deshmukh

7. The continue Statement With the continue statement we can stop the current iteration of the loop, and continue with the next. Prof. Kartiki Deshmukh

8. Example fruits = ["apple", "banana", "cherry"] for x in fruits:   if x == "banana":     continue   print(x ) Output: apple cherry Prof. Kartiki Deshmukh

9. The range() Function The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number. Prof. Kartiki Deshmukh

10. Example for x in range(6):   print(x ) Output: 1 2 3 4 5 Example for x in  range(2, 6):   print(x ) Output: 2 3 4 5 Prof. Kartiki Deshmukh

11. Else in For Loop The  else  keyword in a  for  loop specifies a block of code to be executed when the loop is finished. Prof. Kartiki Deshmukh

12. Example for x in range(6):   print(x) else:   print("Finally finished !") Output: 1 2 3 4 5 Finally finished! Prof. Kartiki Deshmukh

13. The  else  block will NOT be executed if the loop is stopped by a  break  statement . Example for x in range(6):   if x ==  2:  break   print(x) else:   print("Finally finished !") Output: 1 Prof. Kartiki Deshmukh

14. Nested Loops A nested loop is a loop inside a loop. The "inner loop" will be executed one time for each iteration of the "outer loop" Prof. Kartiki Deshmukh

15. Example color = ["red", "big", "tasty"] fruits = ["apple", “mango", "cherry"] for x in color: for y in fruits: print(x, y) Prof. Kartiki Deshmukh

16. Output: red apple red mango red cherry big apple big mango big cherry tasty apple tasty mango tasty cherry Prof. Kartiki Deshmukh

17. while loops With the while loop we can execute a set of statements as long as a condition is true. Prof. Kartiki Deshmukh

18. Example i = 1 while i < 6: print(i) i += 1 Output: 1 2 3 4 5 6 Prof. Kartiki Deshmukh

19. The break Statement With the break statement we can stop the loop even if the while condition is true: Prof. Kartiki Deshmukh

20. Example i = 1 while  i < 6:   print( i )   if  i == 3:     break    i +=  1 Output: 1 2 3 Prof. Kartiki Deshmukh

21. The continue Statement With the continue statement we can stop the current iteration, and continue with the next Prof. Kartiki Deshmukh

22. Example i = 0 while  i < 6:    i += 1   if  i == 3:     continue   print( i ) Output: 1 2 4 5 6 Prof. Kartiki Deshmukh

23. The else Statement With the else statement we can run a block of code once when the condition no longer is true. Prof. Kartiki Deshmukh

24. Example i = 1 while  i < 6:   print( i )    i += 1 else:   print(" i is no longer less than 6 ") Output: 1 2 3 4 5 i is no longer less than 6 Prof. Kartiki Deshmukh