Python-3.4.3/C3/Getting-started-with-strings/English-timed

Tiime	Narration
00:01	Hello Friends. Welcome to the tutorial on "Getting Started with Strings".
00:07	At the end of this tutorial, you will learn to, Define strings in different ways. Concatenate strings. Print a string repeatedly. Access individual elements of the string.
00:24	To record this tutorial, I am using Ubuntu Linux 16.04 operating system Python 3.4.3 and IPython 5.1.0
00:39	To practise this tutorial, you should know how to run basic Python commands on the ipython console
00:48	If not, see the pre-requisite Python tutorials on this website.
00:54	What are strings? In Python, any character within a single/ double/ triple quotes is a string.
01:03	For example: Single, double, and triple quotes can be used to denote a string as shown here.
01:13	Strings in triple quotes can be written in multiple lines.
01:19	We can also define empty strings. String is a collection of characters which cannot be modified after it is created.
01:30	Let us first open the Terminal by pressing Ctrl+Alt+T keys simultaneously. Type ipython3 and press Enter.
01:42	Let us initialise the pylab package.Type %pylab and press Enter.
01:51	Let us clear the terminal. We can assign a string to a variable called a.
01:58	Type a is equal to inside any quotes Hello comma World exclamation mark and Press Enter
02:09	Now let us learn string concatenation. Let us assign strings to variables.
02:16	Type x is equal to inside quotes Hello Press Enter y is equal to inside quotes World Press Enter
02:32	Now, let us add the two strings. z is equal to x plus inside quotes comma plus y plus inside quotes exclamation mark. Press Enter
02:52	print inside parentheses z Press Enter Here x and y are string variables.
03:04	The addition operation performs the concatenation of two strings.
03:09	Here we can see the output of string concatenation.
03:14	Let us clear the terminal. What if we multiply a string with an integer? Let us find out!
03:23	Recall x string. Press Enter x multiplied by 5 Press Enter
03:33	The string Hello is repeated 5 times after multiplying.
03:39	Pause the video. Try this exercise and then resume the video. Obtain the string as shown without typing out all the twenty hyphens.
03:51	Switch to the terminal for solution. Type, s is equal to inside quotes two percentages plus inside quotes hyphen multiplied by twenty plus inside quotes two percentages Press Enter
04:14	print inside parentheses s Press Enter
04:20	Let's now look at accessing individual elements of strings. We can access individual elements in the string using the subscripts.
04:30	Let us clear the terminal. Recall a. Press Enter. Type, a inside square brackets zero press Enter, gives us the first character of the string.
04:47	The indexing starts from 0 and goes up to (n-1). where n is the total number of characters in a string.
04:57	We can access the strings from the end using negative indices.
05:02	a inside square brackets minus one gives us the last element of the string i.e. exclamation mark
05:11	a inside square brackets minus two gives us the second element from the end of the string i.e. d
05:21	Pause the video. Try this exercise and then resume the video. Given a string, s which is Hello World, what is the output of the following
05:33	Switch to the terminal.
05:35	Let us clear the terminal. Type s is equal to inside quotes Hello World press Enter
05:46	s inside square brackets minus five gives W Similarly we will get e for s[-10].
05:59	s inside square brackets minus 15 gives us an IndexError. Since the string given to us is only 11 characters long.
06:12	s inside square brackets 15 again gives IndexError for the same reason.
06:20	Let us attempt to change one of the characters in a string. Let us clear the terminal. Recall x Press Enter
06:31	Let us manipulate x. x inside square brackets zero equal to inside quotes B press Enter
06:44	Why do we get an error? Initially the value of x[0] is ‘H’.
06:52	Now we are trying to assign another value ‘B’ to x[0]. Recall, strings cannot be modified after it is created.
07:02	We can split and join the strings by using the functions : split() and join()
07:08	To join a string, the syntax is str dot join inside parentheses sequence
07:17	Switch to the terminal.
07:19	Let us clear the terminal
07:22	Type s is equal to inside quotes hyphen press Enter seq is equal to inside parentheses a comma b comma c press Enter
07:41	print s dot join' inside parentheses seq press Enter
07:49	We will get output as a hyphen b hyphen c It has joined a, b, c with hyphen.
07:57	To split a string, syntax is str dot split open and close parentheses
08:05	Switch to the terminal Type as shown press Enter print str dot split open and close parentheses press Enter
08:19	We get the output like this. It has split the strings at spaces.
08:25	This brings us to the end of this tutorial.
08:28	In this tutorial, we have learnt to, Define strings in different ways. Concatenate strings. Print a string repeatedly and Access individual elements of the string.
08:42	Here are some self assessment questions for you to solve
08:46	1. Write code to assign the string ’ is called the apostrophe, to variable s 2. How will you change s is equal to hello to s is equal to capital H Hello.
09:01	3. The variables s and t are strings and r is integer.
09:07	They are assigned with the values as shown below, What is the output of s multiplied by r plus t multiplied by r?
09:17	And the answers, The given string can be assigned in this manner Strings cannot be manipulated after it is assigned a value
09:29	The operation s multiplied by r plus t multiplied by r will print each of the two words twice as HelloHelloWorldWorld
09:41	Please post your timed queries in this forum.
09:45	Please post your general queries on Python in this forum.
09:50	FOSSEE team coordinates the TBC project.
09:54	Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India. For more details, visit this website.
10:04	This is Trupti Kini from IIT Bombay signing off. Thank you.

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Pratik kamble