C-and-C++/C2/Relational-Operators/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Relational Operators in C and C++.
00:06	In this tutorial, we will learn about:
00:09	Relational operators like,
00:11	Less than: e.g. a < b
00:14	Greater than: e.g. a > b
00:17	Less than or equal to: e.g. a <= b
00:22	Greater than or equal to: e.g. a >= b
00:27	Equal to: e.g. a == b
00:30	Not equal to: e.g. a != b
00:37	To record this tutorial, I am using: Ubuntu 11.10 as the operating system,
00:42	gcc and g++ Compiler version 4.6.1 in Ubuntu.
00:50	Let us begin with an introduction.
00:53	Relational operators are used to compare integer and floating point numbers.
00:57	Expressions using relational operators return 0 for false and 1 for true.
01:04	Now I will demonstrate the relational operators with the help of a C program.
01:09	I have already made the program.
01:11	So, I'll open the editor and explain the code.
01:15	First, we declare two variables a and b.
01:20	This printf statement prompts the user to enter the values of a and b.
01:26	This scanf statement takes input for the variables a and b.
01:32	Now we have the greater than (>) operator.
01:35	This operator compares the two operands on either side of the operator.
01:38	It returns True if a is greater than b.
01:43	This printf statement is executed if the above condition is true.
01:47	If the above condition is false then it is skipped.
01:50	The control then jumps to the next statement.
01:53	We now have the less than (<) operator.
01:56	This too compares the operands.
01:57	It returns true when a is less than b.
02:02	This printf statement is executed if the above condition is true.
02:06	It is skipped otherwise.
02:09	Let's execute the code till here.
02:13	First comment out the following.
02:16	Type /* (slash asterisk)
02:21	*/ (asterisk slash).
02:24	Click on Save.
02:26	I have saved my file as relational.c.
02:29	Open the terminal window by pressing Ctrl, Alt and T keys simultaneously.
02:35	To compile, type the following on the terminal gcc space relational dot c space -o space rel.
02:49	Press Enter.
02:51	To execute, type ./rel (dot slash rel). Press Enter.
02:56	I enter a as 8 and b as 3.
03:01	The output is displayed:
03:03	8 is greater than 3.
03:07	You can try executing this code with different values of a and b.
03:11	Coming back to the code.
03:14	Delete the comment from here
03:18	and put it here.
03:24	Now we have the less than or equal to (<=) operator.
03:28	This operator compares the two operands on either side of the operator.
03:33	It returns true if a is less than or equal to b.
03:38	This printf statement is executed if the above condition is true.
03:42	If the above condition is false then it is skipped.
03:45	The control then jumps to the next statement.
03:49	Next comes the greater than or equal to (>=) operator.
03:52	It compares a and b and returns true if a is greater than or equal to b.
04:00	If the condition is true then this printf statement will be executed.
04:05	Now let's execute the code till here.
04:07	Click on Save.
04:09	Switch back to the terminal.
04:12	Compile and execute as before.
04:17	I enter a as 8 and b as 3.
04:22	The output is displayed:
04:25	8 is greater than or equal to 3
04:30	Now Coming back to rest of the code.
04:33	Delete the multiline comments from here
04:39	and here.
04:43	We now have the equal to operator.
04:47	It is denoted by double equal signs (==).
04:50	This operator returns true when both operands are equal to one another.
04:57	This printf statement executes when a is equal to b.
05:00	If not, the control then jumps on to the next statement.
05:06	Similarly, we have the not equal to operator.
05:08	This operator returns true when the operands are not equal to one another.
05:15	This printf statement will execute when a is not equal to b.
05:20	Coming to the end of the program. return 0;
05:24	Click on Save.
05:26	Switch back to the terminal.
05:28	Compile and execute as before.
05:32	Enter a as 8 and b as 3.
05:38	The output is displayed on the screen:
05:40	8 is not equal to 3
05:44	So, we see how the relational operators work.
05:48	Try executing this code with different set of inputs.
05:51	Now, writing a similar program in C++ is quite easy.
05:56	There are a few differences in the syntax.
05:59	I have already made the code in C++.
06:04	Here is the code for relational operators in C++.
06:08	Notice that the header is different.
06:12	Also we have the using statement here.
06:15	The output statement in C++ is cout.
06:19	And the input statement in C++ is cin.
06:22	So, apart from these differences, the two codes are very similar.
06:26	Click on Save.
06:28	Please make sure the file is saved with the extension .cpp.
06:32	I have saved my file as relational.cpp.
06:37	Let's compile the code.
06:39	Open the terminal and type g++ relational.cpp space minus o space rel1
06:50	To execute, type ./rel1 (dot slash rel1), press Enter.
06:56	I enter a as 8 and b as 3.
07:00	The output is displayed:
07:02	We see that the output is same as the one in C program.
07:07	Now let us see an error which we can come across.
07:10	Come back to the program.
07:13	Suppose here we replace the 'double equal to' sign with the 'single equal to'.
07:19	Click on Save.
07:21	Come back to the terminal.
07:23	Compile and execute as before.
07:33	Here we see it is showing 3 is equal to 3.
07:37	Come back to our program.
07:40	This is because here we have an assignment operator.
07:43	So value of b is assigned to a.
07:46	Now, let us fix this error.
07:49	Type an equal to sign.
07:51	Click on Save.
07:54	Switch back to the terminal.
07:56	Compile and execute as before.
08:04	The output is now correct.
08:06	Let's summarize the tutorial.
08:08	In this tutorial, we learnt
08:10	relational operators like:
08:12	Less than: e.g. a < b
08:14	Greater than: e.g. a>b
08:17	Less than or equal to: e.g. a<=b
08:22	Greater than or equal to: e.g. a>=b
08:27	Equal to: e.g. a==b
08:29	Not equal to: e.g. a!=b
08:34	As an assignment:
08:35	Write a program that takes the marks of three students as input.
08:39	Compare the marks to see which student has scored the highest.
08:43	Check also if two or more students have scored equal marks.
08:48	Watch the video available at the following link.
08:51	It summarizes the Spoken Tutorial project.
08:54	If you do not have good bandwidth, you can download and watch it.
08:58	The Spoken Tutorial Project Team:
09:00	Conducts workshops using spoken tutorials.
09:03	Gives certificates for those who pass an online test.
09:06	For more details, please write to contact at spoken hyphen tutorial dot org.
09:14	Spoken Tutorial Project is a part of the Talk to a Teacher project.
09:18	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
09:24	More information on this Mission is available at
09:27	spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
09:34	This is Ritwik Joshi from IIT Bombay. Thank you for joining.

Contributors and Content Editors

Ashwini, PoojaMoolya, Pratik kamble, Priyacst, Sakinashaikh, Sandhya.np14