Python/C3/Loops/English-timed

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, 1. Iterate over a sequence using ``for and ``while loops.
07:38	2. Break out of loops using ``break statement.
07:42	3. Skip iterations using ``continue statement.
07:45	4. Use the ``pass statement in a loop.
07:49	Here are some self assessment questions for you to solve
07:52	1. Given range(1 comma 4) ; Write a code to print only the number 1.
08:01	2.Second one is, Which statement do you use to skip iterations. - break - pass - continue
08:10	And the answers,
08:12	1. 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.

Contributors and Content Editors

Gaurav, Kavita salve, Minal, PoojaMoolya, Sneha