Python/C3/Loops/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Hello Friends and Welcome to the tutorial on 'loops' in Python. |
| 00:05 | At the end of this tutorial, you will be able to,
use the for loop use the while loop Use break, continue and pass statements to play around with loops. |
| 00:17 | Before beginning this tutorial,we would suggest you to complete the tutorial on "Getting started with for" and "Conditionals". |
| 00:24 | Let us start our ipython interpreter. |
| 00:28 | Type ipython in the terminal |
| 00:32 | We shall first begin with the while loop. |
| 00:34 | The while loop is used for repeated execution as long as a condition is True . |
| 00:39 | Let us print the squares of all the odd numbers less than 10, using the while loop. |
| 00:45 | Type i = 1 while i less than 10 colon print i multiply by i, i += 2 |
| 01:19 | This loop prints the squares of the odd numbers below 10. |
| 01:23 | The while loop, repeatedly checks if the condition is true and executes the block of code within the loop, if it is. |
| 01:30 | As with any other block in Python, the code within the while block is indented to the right by 4 spaces. |
| 01:41 | Pause the video here, try out the following exercise and resume the video. |
| 01:48 | Write a while loop to print the squares of all the even numbers below 10. |
| 01:55 | Switch to the terminal for solution. |
| 01:58 | Type i = 2, while i less than 10 colon print i multiply by i i += 2 |
| 02:27 | Let us now solve the same problem of printing the squares of all odd numbers less than 10, using the for loop. |
| 02:34 | As we know, the for loop iterates over a list or any other sequential data type. |
| 02:40 | So, we use the range function to get a list of odd numbers below 10, and then iterate over it and print the required stuff. |
| 02:48 | Type for n in range within bracket 1 comma 10 comma 2 colon. print n multiply by n |
| 03:07 | We can see that we got the same output as before. |
| 03:10 | Note that the lines of code are less. |
| 03:13 | Pause the video here, try out the following exercise and resume the video. |
| 03:19 | Write a for loop to print the squares of all the even numbers below 10. |
| 03:24 | Switch to the terminal |
| 03:26 | Type for n in range within bracket 2 comma 10 comma 2 colon. print n multiply by n |
| 03:46 | Let us now look at how to use the keywords, pass , break and continue . |
| 03:52 | As we already know, pass is just a syntactic filler. |
| 03:56 | It is used for the sake of completion of blocks, that do not have any code within them. |
| 04:02 | Type for n in range within bracket 2 comma 10 comma 2 colon pass And Enter. |
| 04:20 | break is used to break out of the innermost loop. |
| 04:24 | The while loop to print the squares of all the odd numbers below 10, can be modified using the break statement, as follows |
| 04:31 | Type = 1,while True colon print i multiply by i i += 2 if i is less than 10 colon break |
| 05:10 | So we got a syntax error because 'if' is not inside the while loop
So type while True colon print i multiply by i, i += 2 if i less than 10 colon break Make sure that 'if' is inside the while loop. |
| 05:42 | continue is used to skip execution of the rest of the loop on this iteration and continue to the end of this iteration. |
| 05:50 | So, we wish to print the squares of all the odd numbers below 10, which are not multiples of 3, we would modify the for loop as follows. |
| 06:03 | So, in terminal, Type for n in range within bracket 1 comma 10 comma 2 colon
if n modulo 3 == 0 colon continue print n multiply by n |
| 06:36 | Now Pause the video here, try out the following exercise and resume the video. |
| 06:41 | Using the continue keyword modify the for loop, with the range(2 comma 10 comma 2) , to print the squares of even numbers below 10, which are multiples of 4. |
| 06:53 | (Do not modify the range function call.) |
| 06:59 | Now Switch to the terminal for solution. |
| 07:02 | Type for n in range within bracket 2 comma 10 comma 2 colon
if n modulo 4 colon continue print n multiply by n |
| 07:30 | This brings us to the end of this tutorial. |
| 07:33 | In this tutorial, we have learnt to, Iterate over a sequence using ``for and ``while loops. |
| 07:38 | Break out of loops using break statement. |
| 07:42 | Skip iterations using continue statement. |
| 07:45 | Use the pass statement in a loop. |
| 07:49 | Here are some self assessment questions for you to solve |
| 07:52 | Given range(1 comma 4) ; Write a code to print only the number 1. |
| 08:01 | Second one is, Which statement do you use to skip iterations. - break - pass - continue |
| 08:10 | And the answers, |
| 08:12 | First one, We can use the break statement in a for loop as, colon colon |
| 08:21 | for i in range within bracket 1 comma 4 colon |
| 08:27 | Then print i break |
| 08:30 | And second one, In order to skip iterations,we make use of the continue statement. |
| 08:37 | Hope you have enjoyed this tutorial and found it useful. |
