Difference between revisions of "Python/C3/Loops/English-timed"
From Script | Spoken-Tutorial
Kavita salve (Talk | contribs) |
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| At the end of this tutorial, you will be able to, | | At the end of this tutorial, you will be able to, | ||
| − | # use the for loop | + | # use the '''for''' loop |
| − | # use the while loop | + | # use the '''while''' loop |
| − | # Use break, continue and pass statements to play around with loops. | + | # Use '''break''', continue and pass statements to play around with loops. |
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Revision as of 16:48, 7 August 2013
| Visual Cue | Narration |
|---|---|
| 0:01 | Hello Friends and Welcome to the tutorial on 'loops' in Python. |
| 0:05 | At the end of this tutorial, you will be able to,
|
| 0:17 | Before beginning this tutorial,we would suggest you to complete the tutorial on "Getting started with for" and "Conditionals". |
| 0:24 | Let us start our ipython interpreter. |
| 0:28 | Type ipython in the terminal |
| 0:32 | We shall first begin with the while loop. |
| 0:34 | The while loop is used for repeated execution as long as a condition is True . |
| 0:39 | Let us print the squares of all the odd numbers less than 10, using the while loop. |
| 0:45 | Type i = 1
while i less than 10 colon
print i multiply by i
i += 2
|
| 1:19 | This loop prints the squares of the odd numbers below 10. |
| 1:23 | The while loop, repeatedly checks if the condition is true and executes the block of code within the loop, if it is. |
| 1:30 | As with any other block in Python, the code within the while block is indented to the right by 4 spaces. |
| 1:41 | Pause the video here, try out the following exercise and resume the video. |
| 1:48 | Write a while loop to print the squares of all the even numbers below 10. |
| 1:55 | Switch to the terminal for solution. |
| 1:58 | Type i = 2
while i less than 10 colon
print i multiply by i
i += 2
|
| 2:27 | Let us now solve the same problem of printing the squares of all odd numbers less than 10, using the for loop. |
| 2:34 | As we know, the for loop iterates over a list or any other sequential data type. |
| 2:40 | 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. |
| 2:48 | Type for n in range within bracket 1 comma 10 comma 2 colon
print n multiply by n |
| 3:07 | We can see that we got the same output as before. |
| 3:10 | Note that the lines of code are less. |
| 3:13 | Pause the video here, try out the following exercise and resume the video. |
| 3:19 | Write a for loop to print the squares of all the even numbers below 10. |
| 3:24 | Switch to the terminal |
| 3:26 | Type for n in range within bracket 2 comma 10 comma 2 colon
print n multiply by n |
| 3:46 | Let us now look at how to use the keywords, pass , break and continue . |
| 3:52 | As we already know, pass is just a syntactic filler. |
| 3:56 | It is used for the sake of completion of blocks, that do not have any code within them. |
| 4:02 | Type for n in range within bracket 2 comma 10 comma 2 colon
pass And Enter. |
| 4:20 | break is used to break out of the innermost loop. |
| 4:24 | The while loop to print the squares of all the odd numbers below 10, can be modified using the break statement, as follows |
| 4:31 | Type = 1
while True colon print i multiply by i i += 2 if i is less than 10 colon break |
| 5:10 | 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. |
| 5:42 | continue is used to skip execution of the rest of the loop on this iteration and continue to the end of this iteration. |
| 5:50 | 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. |
| 6:03 | 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
|
| 6:36 | Now Pause the video here, try out the following exercise and resume the video. |
| 6:41 | 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. |
| 6:53 | (Do not modify the range function call.) |
| 6:59 | Now Switch to the terminal for solution. |
| 7:02 | Type for n in range within bracket 2 comma 10 comma 2 colon
if n modulo 4 colon
continue
print n multiply by n
|
| 7:30 | This brings us to the end of this tutorial. |
| 7:33 | In this tutorial, we have learnt to, 1. Iterate over a sequence using ``for and ``while loops. |
| 7:38 | 2. Break out of loops using ``break statement. |
| 7:42 | 3. Skip iterations using ``continue statement. |
| 7:45 | 4. Use the ``pass statement in a loop. |
| 7:49 | Here are some self assessment questions for you to solve |
| 7:52 | 1. Given range(1 comma 4) ; Write a code to print only the number 1. |
| 8:01 | 2.Second one is, Which statement do you use to skip iterations. - break - pass - continue |
| 8:10 | And the answers, |
| 8:12 | 1. First one, We can use the break statement in a for loop as,
colon colon |
| 8:21 | for i in range within bracket 1 comma 4 colon |
| 8:27 | Then print i break |
| 8:30 | And second one, In order to skip iterations,we make use of the continue statement. |
| 8:37 | Hope you have enjoyed this tutorial and found it useful. |
