C-and-C++/C2/If-And-Else-If-statement/English-timed
From Script | Spoken-Tutorial
Time' | 'Narration |
00.02 | Welcome to the spoken tutorial on Conditional statements in C and C++ |
00.09 | In this tutorial we will learn,
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00.11 | how to execute a single statement.
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00.14 | How to execute group of statements.
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00.17 | We will do this through examples.
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00.20 | 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.
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00.32 | gcc and g++ Compiler version 4.6.1 |
00.38 | Let us start with the Introduction to condition statements.
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00.43 | A statement in a program controls the flow of program execution.
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00.50 | It helps to make decision on, what code is to be executed.
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00.56 | We can check the conditions, whether true or false.
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01.01 | We can execute a single statement or a group of statements. |
01.08 | Let us understand the flow of if statements.
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01.13 | Here, if the condition is true then , statement1 will be executed.
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01.20 | If the condition is false then statement2 will be executed. |
01.29 | Now we will see the flow of else if statement,
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01.32 | Here, if condition1 is true then statement1 will be executed.
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01.41 | If condition1 is false then it will check for another condition that is condition2.
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01.50 | If condition2 is true, then statement3 will be executed.
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01.55 | And If condition2 is false, then statement2 will be executed |
02.03 | Now Let us move on to our program.
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02.06 | I have already typed the code on the editor.
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02.09 | So let me open it.
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02.13 | Note that our filename is ifstmt.c |
02.19 | In this program we will calculate the sum of two numbers and will check a few conditions. |
02.27 | Let me explain the code now.
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02.31 | 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. |
02.47 | Here we are asking for user input.
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02.49 | User will enter the values of a and b.
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02.52 | The values will be stored in variable a and variable b. |
02.58 | The 'scanf() reads data from the console.
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03.02 | It then stores the result in the given variable.
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03.06 | The format specifier in the scanf() helps to know the type of data.
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03.11 | Like here we have %d it denotes that we are dealing with integer data type. |
03.19 | Here we add the values of a and b.
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03.22 | We will store the result in sum. |
03.26 | Then we print the result. |
03.29 | This is our if statement. |
03.31 | 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. |
03.43 | 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 ifstmt.c -o 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. |
04.32 | 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. |
04.49 | We will check another condition. |
04.53 | Let me remove the comment from here. |
04.57 | 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. Let us execute as before. |
05.27 | 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. |
05.39 | Sum is greater than 10 and less than 20. |
05.43 | Let me clear the prompt. 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. |
06.08 | Now let us execute and see. come back to our terminal. |
06.12 | 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.
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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. |
07.44 | The output is displayed as |
07.46 | 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. |
08.00 | 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 .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 . |
08.36 | let us replace printf statement with cout statement. |
08.40 | Click on Replace all and click on Close
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08.46 | Now delete the closing brackets here. |
08.50 | 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++.
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09.06 | 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. |
09.32 | 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. |
09.54 | Now again delete the closing bracket here and here. |
09.59 | Now Click on Save |
10.03 | 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 |
10.21 | 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 |
10.33 | 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. |
10.53 | Sum is greater than 20. |
10.56 | This brings us to the end of this tutorial. |
10.59 | Now come back to our slides. |
11.03 | Let us summarize. |
11.04 | In this tutorial we learned, if statement eg. if(condition)
{…........ } |
11.12 | And else if statement eg. else if(condition)
{…......... } |
11.18 | As an assignment, |
11.19 | 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. |
11.39 | Watch the video available at the link shown below. http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial |
11.41 | It summarizes the Spoken Tutorial project. |
11.44 | If you do not have good bandwidth, you can download and watch it. |
11.49 | The Spoken Tutorial Project Team, |
11.51 | Conducts workshops using spoken tutorials. |
11.54 | Gives certificates to those who pass an online test. |
11.58 | For more details, please write to, contact [at] spoken hyphen tutorial dot org. |
12.05 | 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. |
12.16 | More information on this Mission is available at the link shown below. (http://spoken-tutorial.org\NMEICT-Intro) |
12.21 | This is Ashwini Patil from IIT Bombay
Thank You for watching. |
Contributors and Content Editors
Ashwini, Devraj, Kavita salve, Krupali, PoojaMoolya, Priyacst, Sakinashaikh, Sandhya.np14, Sneha