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

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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.
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08:58 The Spoken Tutorial Project Team:
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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