C-and-C++/C2/If-And-Else-If-statement/English-timed

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Time Narration
00:02 Welcome to the spoken tutorial on Conditional statements in C and C++
00:08 In this tutorial we will learn,


00:11 how to execute a single statement.


00:14 How to execute group of statements.


00:16 We will do this through examples.


00:19 We will also see some common errors and their solutions.
00:25 To record this tutorial, I am using, Ubuntu Operating system version 11.10.


00:31 gcc and g++ Compiler version 4.6.1
00:38 Let us start with the Introduction to condition statements.


00:43 A statement in a program controls the flow of program execution.


00:49 It helps to make decision on, what code is to be executed.


00:55 We can check the conditions, whether true or false.


01:00 We can execute a single statement or a group of statements.
01:07 Let us understand the flow of if statements.


01:13 Here, if the condition is true then , statement1 will be executed.


01:20 If the condition is false then statement2 will be executed.
01:29 Now we will see the flow of else if statement,


01:32 Here, if condition1 is true then statement1 will be executed.


01:41 If condition1 is false then it will check for another condition that is condition2.


01:49 If condition2 is true, then statement3 will be executed.


01:54 And If condition2 is false, then statement2 will be executed
02:02 Now Let us move on to our program.


02:06 I have already typed the code on the editor.


02:09 So let me open it.


02:13 Note that our filename is ifstmt.c
02:18 In this program we will calculate the sum of two numbers and will check a few conditions.
02:26 Let me explain the code now.


02:30 This is our header file.
02:34 This is our main function.
02:38 Here we have declared three integer variables a, b and sum.
02:46 Here we are asking for user input.


02:49 User will enter the values of a and b.


02:52 The values will be stored in variable a and variable b.
02:58 The scanf() function reads data from the console.


03:02 It then stores the result in the given variable.


03:06 The format specifier in the scanf() helps to know the type of data.


03:10 Like here we have %d it denotes that we are dealing with integer data type.
03:18 Here we add the values of a and b.


03:22 We will store the result in sum.
03:25 Then we print the result.
03:29 This is our if statement.
03:30 Here, we check the condition whether sum is greater than 20.
03:36 If the condition is true, then we print Sum is greater than 20.
03:42 Now let me comment out these lines.
03:48 This is our return statement.
03:51 Now click on Save
03:53 First we will see the execution of if statement.
03:58 Please open the terminal window by pressing,Ctrl, Alt and T keys simultaneously on your keyboard.
04:09 To compile type, gcc space ifstmt dot c space -o space ifand press enter
04:20 To execute type, ./if press enter
04:26 it is displayed as,
04:27 Enter the value of a and b.
04:31 I will give the values as 10 and 12.
04:38 The output is displayed as Sum of a and b is 22. Sum is greater than 20.
04:45 Now come back to our program.
04:48 We will check another condition.
04:52 Let me remove the comment from here.
04:56 I will give the comment here.
05:00 Now click on Save.
05:03 This is our else-if statement.
05:05 Here, we check another condition whether Sum is greater than 10
05:11 If the condition is true then we print Sum is greater than 10 and less than 20.
05:18 Now come back to our terminal.
05:20 Let us compile as before.
05:23 Let us execute as before.
05:26 It is displayed as,
05:28 Enter the value of a and b.
05:30 I will give the values as 10 and 2.
05:35 The output is displayed as: Sum of a and b is 12.
05:38 Sum is greater than 10 and less than 20.
05:42 Let me clear the prompt.


05:44 Now come back to our program.
05:48 I will remove the comment from here and here. Now click on save,
05:56 If both the above conditions are false, then we print Sum is less than 10.
06:04 This is our else statement.
06:07 Now let us execute and see. come back to our terminal.
06:11 Let us compile as before. Let us execute as before.
06:18 Here it is displayed as,
06:19 Enter the value of a and b.
06:22 I will give the values as 3 and 5.
06:27 the output is as, sum of a and b is 8.
06:31 Sum is less than 10.
06:34 Now we will see some common errors which we can come across.
06:38 Come back to our program.
06:41 Suppose, here at the end of if statement I will type a semicolon.
06:47 Let see what will happen. Click on Save.


06:50 Let us execute. Come back to our terminal.
06:53 Let us compile as before.
06:56 We see an error: else without a previous if
07:02 Come back to our program.It is an syntax error.
07:07 If statement will never terminate with a semicolon.
07:10 And the else if statement will never work without an if.
07:16 Let us fix the error. Delete the semicolon ; here
07:22 Now Click on Save.
07:25 Let us execute. Come back to the terminal.
07:29 Let us compile as before. Let us execute as before.
07:35 Enter the value of a and b
07:37 I will give the values as 3 and 6.
07:43 The output is displayed as
07:45 Sum of a and b is 9. Sum is less than 10.
07:52 NOW WE WILL SEE HOW TO EXECUTE THE SAME PROGRAM IN C++.
07:57 Come back to our program.
07:59 I will change a few things here.
08:03 Press Shift, Ctrl and S keys simultaneously on your keyboard.
08:11 Now save the file with an extension dot cpp and click on Save
08:20 We will change the header file as, iostream
08:26 Let us include the using statement here.
08:30 Now click on the search for and replace text option .
08:35 Let us replace the printf statement with the cout statement.
08:40 Click on Replace all and click on Close


08:46 Now delete the closing brackets here.
08:49 Replace the scanf statement with the cin statement.
08:54 Type cin and two closing angle brackets >>
09:00 As we use cin >> function to read a line in C++.


09:05 Now delete the format specifiers.
09:09 Delete the comma and ampersand &
09:12 Delete the comma here and type two closing angle brackets.
09:17 Again delete the ampersandand the closing brackets. Now Click on Save.
09:25 Here delete the closing bracket and the comma.
09:31 Now delete the 'backslash n' and 'format specifier

'

09:37 Now Type two opening brackets
09:42 Again type two opening angle brackets and within the double quotes type backslash n “\n”.
09:49 Here also we will delete the closing bracket.
09:53 Now again delete the closing bracket here and here.
09:59 Now Click on Save
10:02 Let us execute.
10:04 Come back to the terminal .Let me clear the prompt.
10:10 To compile type g++ space ifstmt.cpp space -o space if1
10:20 Here we have if1 because we don't want to overwrite the output parameter if for the file ifstmt.c
10:31 Now Press Enter
10:32 To execute type ./if1 and Press Enter
10:39 Enter the value of a and b. I will give the values as 20 and 10.
10:48 The output is displayed as, Sum of a and b is 30.
10:52 Sum is greater than 20.
10:56 This brings us to the end of this tutorial.
10:59 Now come back to our slides.
11:02 Let us summarize.
11:04 In this tutorial we learned, if statement eg. if(condition)


11:11 And else if statement eg. else if(condition)
11:17 As an assignment,
11:18 Write a program to check a is greater than b or less than b.
11:24 Hint: use if statement.
11:28 Write another program to check which value is greater a, b or c.
11:34 Hint: use else-if statement.
11:38 Watch the video available at the link shown below.
11:41 It summarizes the Spoken Tutorial project.
11:44 If you do not have good bandwidth, you can download and watch it.
11:48 The Spoken Tutorial Project Team,
11:50 Conducts workshops using spoken tutorials.
11:54 Gives certificates to those who pass an online test.
11:57 For more details, please write to, contact @ spoken hyphen tutorial dot org.
12:04 Spoken Tutorial Project is a part of the Talk to a Teacher project.
12:09 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
12:15 More information on this Mission is available at the link shown below.
12:20 This is Ashwini Patil from IIT BombayA

Thank You for watching.