Difference between revisions of "C-and-C++/C2/If-And-Else-If-statement/English-timed"
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− | || | + | || Time |
− | || | + | || Narration |
|- | |- | ||
− | | 00 | + | | 00:02 |
| Welcome to the spoken tutorial on '''Conditional statements in C and C++''' | | Welcome to the spoken tutorial on '''Conditional statements in C and C++''' | ||
|- | |- | ||
− | | 00 | + | | 00:08 |
| In this tutorial we will learn, | | In this tutorial we will learn, | ||
|- | |- | ||
− | | 00 | + | | 00:11 |
| how to execute a single '''statement'''. | | how to execute a single '''statement'''. | ||
|- | |- | ||
− | | 00 | + | | 00:14 |
| How to execute group of '''statements'''. | | How to execute group of '''statements'''. | ||
|- | |- | ||
− | | 00 | + | | 00:16 |
| We will do this through examples. | | We will do this through examples. | ||
|- | |- | ||
− | | 00 | + | | 00:19 |
| We will also see some common errors and their solutions. | | We will also see some common errors and their solutions. | ||
|- | |- | ||
− | | 00 | + | | 00:25 |
| To record this tutorial, I am using, '''Ubuntu Operating system''' version 11.10. | | To record this tutorial, I am using, '''Ubuntu Operating system''' version 11.10. | ||
|- | |- | ||
− | | 00 | + | | 00:31 |
| '''gcc''' and '''g++ Compiler''' version 4.6.1 | | '''gcc''' and '''g++ Compiler''' version 4.6.1 | ||
|- | |- | ||
− | | 00 | + | | 00:38 |
| Let us start with the Introduction to condition '''statements'''. | | Let us start with the Introduction to condition '''statements'''. | ||
|- | |- | ||
− | | 00 | + | | 00:43 |
| A '''statement''' in a program controls the flow of program execution. | | A '''statement''' in a program controls the flow of program execution. | ||
|- | |- | ||
− | | 00 | + | | 00:49 |
| It helps to make decision on, what code is to be executed. | | It helps to make decision on, what code is to be executed. | ||
|- | |- | ||
− | | 00 | + | | 00:55 |
|We can check the conditions, whether true or false. | |We can check the conditions, whether true or false. | ||
|- | |- | ||
− | | 01 | + | | 01:00 |
| We can execute a single statement or a group of statements. | | We can execute a single statement or a group of statements. | ||
|- | |- | ||
− | | 01 | + | | 01:07 |
| Let us understand the flow of if statements. | | Let us understand the flow of if statements. | ||
|- | |- | ||
− | | 01 | + | | 01:13 |
| Here, if the condition is true then , '''statement1''' will be executed. | | Here, if the condition is true then , '''statement1''' will be executed. | ||
|- | |- | ||
− | | 01 | + | | 01:20 |
| If the condition is false then '''statement2''' will be executed. | | If the condition is false then '''statement2''' will be executed. | ||
|- | |- | ||
− | | 01 | + | | 01:29 |
| Now we will see the flow of else if '''statement''', | | Now we will see the flow of else if '''statement''', | ||
|- | |- | ||
− | | 01 | + | | 01:32 |
| Here, if '''condition1''' is true then '''statement1''' will be executed. | | Here, if '''condition1''' is true then '''statement1''' will be executed. | ||
|- | |- | ||
− | | 01 | + | | 01:41 |
| If '''condition1''' is false then it will check for another condition that is '''condition2'''. | | If '''condition1''' is false then it will check for another condition that is '''condition2'''. | ||
|- | |- | ||
− | | 01 | + | | 01:49 |
| If '''condition2''' is true, then '''statement3''' will be executed. | | If '''condition2''' is true, then '''statement3''' will be executed. | ||
|- | |- | ||
− | | 01 | + | | 01:54 |
| And If '''condition2''' is false, then '''statement2''' will be executed | | And If '''condition2''' is false, then '''statement2''' will be executed | ||
|- | |- | ||
− | | 02 | + | | 02:02 |
| Now Let us move on to our program. | | Now Let us move on to our program. | ||
|- | |- | ||
− | | 02 | + | | 02:06 |
| I have already typed the code on the editor. | | I have already typed the code on the editor. | ||
|- | |- | ||
− | | 02 | + | | 02:09 |
| So let me open it. | | So let me open it. | ||
|- | |- | ||
− | | 02 | + | | 02:13 |
| Note that our filename is '''ifstmt.c''' | | Note that our filename is '''ifstmt.c''' | ||
|- | |- | ||
− | | 02 | + | | 02:18 |
| In this program we will calculate the sum of two numbers and will check a few conditions. | | In this program we will calculate the sum of two numbers and will check a few conditions. | ||
|- | |- | ||
− | | 02 | + | | 02:26 |
| Let me explain the code now. | | Let me explain the code now. | ||
|- | |- | ||
− | | 02 | + | | 02:30 |
| This is our '''header file.''' | | This is our '''header file.''' | ||
|- | |- | ||
− | | 02 | + | | 02:34 |
| This is our '''main function.''' | | This is our '''main function.''' | ||
|- | |- | ||
− | | 02 | + | | 02:38 |
| Here we have declared three integer '''variables''' '''a, b and sum.''' | | Here we have declared three integer '''variables''' '''a, b and sum.''' | ||
|- | |- | ||
− | | 02 | + | | 02:46 |
| Here we are asking for user input. | | Here we are asking for user input. | ||
|- | |- | ||
− | | 02 | + | | 02:49 |
| User will enter the values of a and b. | | User will enter the values of a and b. | ||
|- | |- | ||
− | | 02 | + | | 02:52 |
| The values will be stored in '''variable a''' and '''variable b.''' | | The values will be stored in '''variable a''' and '''variable b.''' | ||
|- | |- | ||
− | | 02 | + | | 02:58 |
|The '''scanf()''' function reads data from the console. | |The '''scanf()''' function reads data from the console. | ||
|- | |- | ||
− | | 03 | + | | 03:02 |
| It then stores the result in the given '''variable.''' | | It then stores the result in the given '''variable.''' | ||
|- | |- | ||
− | | 03 | + | | 03:06 |
| The''' format specifier '''in the''' scanf() '''helps to know the type of data. | | The''' format specifier '''in the''' scanf() '''helps to know the type of data. | ||
|- | |- | ||
− | | 03 | + | | 03:10 |
| Like here we have %d it denotes that we are dealing with integer data type. | | Like here we have %d it denotes that we are dealing with integer data type. | ||
|- | |- | ||
− | | 03 | + | | 03:18 |
| Here we add the values of''' a''' and '''b.''' | | Here we add the values of''' a''' and '''b.''' | ||
|- | |- | ||
− | | 03 | + | | 03:22 |
| We will store the result in '''sum.''' | | We will store the result in '''sum.''' | ||
|- | |- | ||
− | | 03 | + | | 03:25 |
| Then we print the result. | | Then we print the result. | ||
|- | |- | ||
− | | 03 | + | | 03:29 |
| This is our '''if statement.''' | | This is our '''if statement.''' | ||
|- | |- | ||
− | | 03 | + | | 03:30 |
|Here, we check the condition whether '''sum''' is greater than 20. | |Here, we check the condition whether '''sum''' is greater than 20. | ||
|- | |- | ||
− | | 03 | + | | 03:36 |
|If the condition is true, then we print '''Sum''' is greater than 20. | |If the condition is true, then we print '''Sum''' is greater than 20. | ||
|- | |- | ||
− | | 03 | + | | 03:42 |
| Now let me comment out these lines. | | Now let me comment out these lines. | ||
|- | |- | ||
− | |03 | + | |03:48 |
|This is our return statement. | |This is our return statement. | ||
|- | |- | ||
− | | 03 | + | | 03:51 |
| Now click on '''Save''' | | Now click on '''Save''' | ||
|- | |- | ||
− | | 03 | + | | 03:53 |
|First we will see the execution of if statement. | |First we will see the execution of if statement. | ||
|- | |- | ||
− | | 03 | + | | 03:58 |
| Please open the terminal window by pressing,'''Ctrl, Alt and T''' keys simultaneously on your keyboard. | | Please open the terminal window by pressing,'''Ctrl, Alt and T''' keys simultaneously on your keyboard. | ||
|- | |- | ||
− | |04 | + | |04:09 |
| To compile type, '''gcc space ifstmt dot c space -o space if'''and press enter | | To compile type, '''gcc space ifstmt dot c space -o space if'''and press enter | ||
|- | |- | ||
− | | 04 | + | | 04:20 |
| To execute type, '''./if''' press enter | | To execute type, '''./if''' press enter | ||
|- | |- | ||
− | | 04 | + | | 04:26 |
| it is displayed as, | | it is displayed as, | ||
|- | |- | ||
− | | 04 | + | | 04:27 |
|Enter the value of a and b. | |Enter the value of a and b. | ||
|- | |- | ||
− | | 04 | + | | 04:31 |
|I will give the values as 10 and 12. | |I will give the values as 10 and 12. | ||
|- | |- | ||
− | | 04 | + | | 04:38 |
|The output is displayed as Sum of a and b is 22. Sum is greater than 20. | |The output is displayed as Sum of a and b is 22. Sum is greater than 20. | ||
|- | |- | ||
− | | 04 | + | | 04:45 |
| Now come back to our program. | | Now come back to our program. | ||
|- | |- | ||
− | | 04 | + | | 04:48 |
| We will check another condition. | | We will check another condition. | ||
|- | |- | ||
− | | 04 | + | | 04:52 |
|Let me remove the comment from here. | |Let me remove the comment from here. | ||
|- | |- | ||
− | | 04 | + | | 04:56 |
|I will give the comment here. | |I will give the comment here. | ||
|- | |- | ||
− | | 05 | + | | 05:00 |
|Now click on '''Save.''' | |Now click on '''Save.''' | ||
|- | |- | ||
− | | 05 | + | | 05:03 |
| This is our else-if statement. | | This is our else-if statement. | ||
|- | |- | ||
− | | 05 | + | | 05:05 |
|Here, we check another condition whether '''Sum''' is greater than 10 | |Here, we check another condition whether '''Sum''' is greater than 10 | ||
|- | |- | ||
− | | 05 | + | | 05:11 |
|If the condition is true then we print '''Sum''' is greater than 10 and less than 20. | |If the condition is true then we print '''Sum''' is greater than 10 and less than 20. | ||
|- | |- | ||
− | | 05 | + | | 05:18 |
| Now come back to our terminal. | | Now come back to our terminal. | ||
|- | |- | ||
− | | 05 | + | | 05:20 |
|Let us compile as before. | |Let us compile as before. | ||
|- | |- | ||
− | | 05 | + | | 05:23 |
|Let us execute as before. | |Let us execute as before. | ||
|- | |- | ||
− | | 05 | + | | 05:26 |
| It is displayed as, | | It is displayed as, | ||
|- | |- | ||
− | | 05 | + | | 05:28 |
|Enter the value of a and b. | |Enter the value of a and b. | ||
|- | |- | ||
− | | 05 | + | | 05:30 |
| I will give the values as 10 and 2. | | I will give the values as 10 and 2. | ||
|- | |- | ||
− | | 05 | + | | 05:35 |
|The output is displayed as: Sum of a and b is 12. | |The output is displayed as: Sum of a and b is 12. | ||
|- | |- | ||
− | | 05 | + | | 05:38 |
|Sum is greater than 10 and less than 20. | |Sum is greater than 10 and less than 20. | ||
|- | |- | ||
− | | 05 | + | | 05:42 |
|Let me clear the prompt. | |Let me clear the prompt. | ||
|- | |- | ||
− | | 05 | + | | 05:44 |
| Now come back to our program. | | Now come back to our program. | ||
|- | |- | ||
− | | 05 | + | | 05:48 |
| I will remove the comment from here and here. Now click on save, | | I will remove the comment from here and here. Now click on save, | ||
|- | |- | ||
− | | 05 | + | | 05:56 |
| If both the above conditions are false, then we print Sum is less than 10. | | If both the above conditions are false, then we print Sum is less than 10. | ||
|- | |- | ||
− | | 06 | + | | 06:04 |
|This is our else statement. | |This is our else statement. | ||
|- | |- | ||
− | | 06 | + | | 06:07 |
| Now let us execute and see. come back to our terminal. | | Now let us execute and see. come back to our terminal. | ||
|- | |- | ||
− | | 06 | + | | 06:11 |
|Let us compile as before. Let us execute as before. | |Let us compile as before. Let us execute as before. | ||
|- | |- | ||
− | | 06 | + | | 06:18 |
− | + | | Here it is displayed as, | |
|- | |- | ||
− | | 06 | + | | 06:19 |
|Enter the value of a and b. | |Enter the value of a and b. | ||
|- | |- | ||
− | | 06 | + | | 06:22 |
|I will give the values as 3 and 5. | |I will give the values as 3 and 5. | ||
|- | |- | ||
− | | 06 | + | | 06:27 |
| the output is as, sum of a and b is 8. | | the output is as, sum of a and b is 8. | ||
|- | |- | ||
− | | 06 | + | | 06:31 |
|Sum is less than 10. | |Sum is less than 10. | ||
|- | |- | ||
− | | 06 | + | | 06:34 |
| Now we will see some common errors which we can come across. | | Now we will see some common errors which we can come across. | ||
|- | |- | ||
− | | 06 | + | | 06:38 |
|Come back to our program. | |Come back to our program. | ||
|- | |- | ||
− | | 06 | + | | 06:41 |
| Suppose, here at the end of if statement I will type a semicolon. | | Suppose, here at the end of if statement I will type a semicolon. | ||
|- | |- | ||
− | | 06 | + | | 06:47 |
|Let see what will happen. Click on '''Save.''' | |Let see what will happen. Click on '''Save.''' | ||
Line 374: | Line 374: | ||
|- | |- | ||
− | | 06 | + | | 06:50 |
| Let us execute. Come back to our terminal. | | Let us execute. Come back to our terminal. | ||
|- | |- | ||
− | | 06 | + | | 06:53 |
|Let us compile as before. | |Let us compile as before. | ||
|- | |- | ||
− | | 06 | + | | 06:56 |
| We see an error: else without a previous if | | We see an error: else without a previous if | ||
|- | |- | ||
− | | 07 | + | | 07:02 |
| Come back to our program.It is an syntax error. | | Come back to our program.It is an syntax error. | ||
|- | |- | ||
− | | 07 | + | | 07:07 |
|If statement will never terminate with a semicolon. | |If statement will never terminate with a semicolon. | ||
|- | |- | ||
− | | 07 | + | | 07:10 |
|And the else if statement will never work without an if. | |And the else if statement will never work without an if. | ||
|- | |- | ||
− | | 07 | + | | 07:16 |
| Let us fix the error. Delete the semicolon ; here | | Let us fix the error. Delete the semicolon ; here | ||
|- | |- | ||
− | | 07 | + | | 07:22 |
| Now Click on '''Save.''' | | Now Click on '''Save.''' | ||
|- | |- | ||
− | | 07 | + | | 07:25 |
| Let us execute. Come back to the terminal. | | Let us execute. Come back to the terminal. | ||
|- | |- | ||
− | | 07 | + | | 07:29 |
| Let us compile as before. Let us execute as before. | | Let us compile as before. Let us execute as before. | ||
|- | |- | ||
− | | 07 | + | | 07:35 |
|Enter the value of a and b | |Enter the value of a and b | ||
|- | |- | ||
− | | 07 | + | | 07:37 |
|I will give the values as 3 and 6. | |I will give the values as 3 and 6. | ||
|- | |- | ||
− | | 07 | + | | 07:43 |
|The output is displayed as | |The output is displayed as | ||
|- | |- | ||
− | | 07 | + | | 07:45 |
|Sum of a and b is 9. Sum is less than 10. | |Sum of a and b is 9. Sum is less than 10. | ||
|- | |- | ||
− | | 07 | + | | 07:52 |
− | + | | NOW WE WILL SEE HOW TO EXECUTE THE SAME PROGRAM IN C++. | |
|- | |- | ||
− | | 07 | + | | 07:57 |
|Come back to our program. | |Come back to our program. | ||
|- | |- | ||
− | | 07 | + | | 07:59 |
| I will change a few things here. | | I will change a few things here. | ||
|- | |- | ||
− | | 08 | + | | 08:03 |
| Press '''Shift, Ctrl and S''' keys simultaneously on your keyboard.''' | | Press '''Shift, Ctrl and S''' keys simultaneously on your keyboard.''' | ||
|- | |- | ||
− | | 08 | + | | 08:11 |
|Now save the file with an extension ''' dot cpp''' and''' '''click''' '''on''' Save''' | |Now save the file with an extension ''' dot cpp''' and''' '''click''' '''on''' Save''' | ||
|- | |- | ||
− | | 08 | + | | 08:20 |
| We will change the header file as, '''iostream''' | | We will change the header file as, '''iostream''' | ||
|- | |- | ||
− | | 08 | + | | 08:26 |
| Let us include the '''using '''statement here. | | Let us include the '''using '''statement here. | ||
|- | |- | ||
− | | 08 | + | | 08:30 |
| Now click on the search for and replace text option . | | Now click on the search for and replace text option . | ||
|- | |- | ||
− | | 08 | + | | 08:35 |
|Let us replace the '''printf '''statement with the '''cout''' '''statement.''' | |Let us replace the '''printf '''statement with the '''cout''' '''statement.''' | ||
|- | |- | ||
− | | 08 | + | | 08:40 |
|Click on '''Replace all''' and click on '''Close''' | |Click on '''Replace all''' and click on '''Close''' | ||
Line 471: | Line 471: | ||
|- | |- | ||
− | | 08 | + | | 08:46 |
| Now delete the closing brackets here. | | Now delete the closing brackets here. | ||
|- | |- | ||
− | | 08 | + | | 08:49 |
|Replace the '''scanf''' statement with the '''cin''' statement. | |Replace the '''scanf''' statement with the '''cin''' statement. | ||
|- | |- | ||
− | | 08 | + | | 08:54 |
|Type '''cin and two closing angle brackets >>''' | |Type '''cin and two closing angle brackets >>''' | ||
|- | |- | ||
− | | 09 | + | | 09:00 |
|As we use '''cin >> function''' to read a line in C++. | |As we use '''cin >> function''' to read a line in C++. | ||
|- | |- | ||
− | | 09 | + | | 09:05 |
| Now delete the '''format specifiers'''. | | Now delete the '''format specifiers'''. | ||
|- | |- | ||
− | | 09 | + | | 09:09 |
|Delete the '''comma''' and '''ampersand''' &''' | |Delete the '''comma''' and '''ampersand''' &''' | ||
|- | |- | ||
− | | 09 | + | | 09:12 |
|Delete the comma here and type two closing angle brackets. | |Delete the comma here and type two closing angle brackets. | ||
|- | |- | ||
− | | 09 | + | | 09:17 |
|Again delete the '''ampersand'''and the closing brackets. Now Click on '''Save'''. | |Again delete the '''ampersand'''and the closing brackets. Now Click on '''Save'''. | ||
|- | |- | ||
− | | 09 | + | | 09:25 |
| Here delete the closing bracket and the comma. | | Here delete the closing bracket and the comma. | ||
|- | |- | ||
− | | 09 | + | | 09:31 |
|Now delete the ''''backslash n'''' and ''''format specifier''' | |Now delete the ''''backslash n'''' and ''''format specifier''' | ||
' | ' | ||
|- | |- | ||
− | | 09 | + | | 09:37 |
| Now Type two opening brackets | | Now Type two opening brackets | ||
|- | |- | ||
− | | 09 | + | | 09:42 |
|Again type two opening angle brackets and''' within the double quotes type backslash n “\n”.''' | |Again type two opening angle brackets and''' within the double quotes type backslash n “\n”.''' | ||
|- | |- | ||
− | | 09 | + | | 09:49 |
|Here also we will delete the closing bracket. | |Here also we will delete the closing bracket. | ||
|- | |- | ||
− | | 09 | + | | 09:53 |
|Now again delete the closing bracket here and here. | |Now again delete the closing bracket here and here. | ||
|- | |- | ||
− | | 09 | + | | 09:59 |
|Now Click on '''Save''' | |Now Click on '''Save''' | ||
|- | |- | ||
− | | 10 | + | | 10:02 |
| Let us execute. | | Let us execute. | ||
|- | |- | ||
− | | 10 | + | | 10:04 |
|| Come back to the terminal .Let me clear the prompt. | || Come back to the terminal .Let me clear the prompt. | ||
|- | |- | ||
− | | 10 | + | | 10:10 |
|To compile type '''g++ space ifstmt.cpp space -o space if1''' | |To compile type '''g++ space ifstmt.cpp space -o space if1''' | ||
|- | |- | ||
− | | 10 | + | | 10:20 |
|Here we have '''if1''' because we don't want to overwrite the output parameter '''if '''for the file ifstmt.c | |Here we have '''if1''' because we don't want to overwrite the output parameter '''if '''for the file ifstmt.c | ||
|- | |- | ||
− | | 10 | + | | 10:31 |
|Now Press '''Enter''' | |Now Press '''Enter''' | ||
|- | |- | ||
− | | 10 | + | | 10:32 |
|To execute type ./if1 and Press '''Enter''' | |To execute type ./if1 and Press '''Enter''' | ||
|- | |- | ||
− | | 10 | + | | 10:39 |
|Enter the value of''' a''' and '''b'''. I will give the values as 20 and 10. | |Enter the value of''' a''' and '''b'''. I will give the values as 20 and 10. | ||
|- | |- | ||
− | | 10 | + | | 10:48 |
|The output is displayed as, Sum of a and b is '''30'''. | |The output is displayed as, Sum of a and b is '''30'''. | ||
|- | |- | ||
− | | 10 | + | | 10:52 |
|Sum is greater than 20. | |Sum is greater than 20. | ||
|- | |- | ||
− | | 10 | + | | 10:56 |
|This brings us to the end of this tutorial. | |This brings us to the end of this tutorial. | ||
|- | |- | ||
− | | 10 | + | | 10:59 |
| Now come back to our slides. | | Now come back to our slides. | ||
|- | |- | ||
− | | 11 | + | | 11:02 |
| Let us summarize. | | Let us summarize. | ||
|- | |- | ||
− | | 11 | + | | 11:04 |
|In this tutorial we learned, if statement eg. if(condition) | |In this tutorial we learned, if statement eg. if(condition) | ||
|- | |- | ||
− | | 11 | + | | 11:11 |
| And else if statement eg. else if(condition) | | And else if statement eg. else if(condition) | ||
|- | |- | ||
− | | 11 | + | | 11:17 |
| As an assignment, | | As an assignment, | ||
|- | |- | ||
− | | 11 | + | | 11:18 |
|Write a program to check '''a''' is greater than '''b''' or less than '''b.''' | |Write a program to check '''a''' is greater than '''b''' or less than '''b.''' | ||
|- | |- | ||
− | | 11 | + | | 11:24 |
|'''Hint: ''' use if statement. | |'''Hint: ''' use if statement. | ||
|- | |- | ||
− | | 11 | + | | 11:28 |
|Write another program to check which value is greater '''a,''' '''b''' or '''c.''' | |Write another program to check which value is greater '''a,''' '''b''' or '''c.''' | ||
|- | |- | ||
− | | 11 | + | | 11:34 |
|'''Hint:''' use else-if statement. | |'''Hint:''' use else-if statement. | ||
|- | |- | ||
− | | 11 | + | | 11:38 |
| Watch the video available at the link shown below. | | Watch the video available at the link shown below. | ||
|- | |- | ||
− | | 11 | + | | 11:41 |
|It summarizes the Spoken Tutorial project. | |It summarizes the Spoken Tutorial project. | ||
|- | |- | ||
− | | 11 | + | | 11:44 |
|If you do not have good bandwidth, you can download and watch it. | |If you do not have good bandwidth, you can download and watch it. | ||
|- | |- | ||
− | |11 | + | |11:48 |
|| The Spoken Tutorial Project Team, | || The Spoken Tutorial Project Team, | ||
|- | |- | ||
− | | 11 | + | | 11:50 |
|Conducts workshops using spoken tutorials. | |Conducts workshops using spoken tutorials. | ||
|- | |- | ||
− | | 11 | + | | 11:54 |
|Gives certificates to those who pass an online test. | |Gives certificates to those who pass an online test. | ||
|- | |- | ||
− | | 11 | + | | 11:57 |
|For more details, please write to, contact @ spoken hyphen tutorial dot org. | |For more details, please write to, contact @ spoken hyphen tutorial dot org. | ||
|- | |- | ||
− | | 12 | + | | 12:04 |
| Spoken Tutorial Project is a part of the Talk to a Teacher project. | | Spoken Tutorial Project is a part of the Talk to a Teacher project. | ||
|- | |- | ||
− | | 12 | + | | 12:09 |
|It is supported by the National Mission on Education through ICT, MHRD, Government of India. | |It is supported by the National Mission on Education through ICT, MHRD, Government of India. | ||
|- | |- | ||
− | | 12 | + | | 12:15 |
|More information on this Mission is available at the link shown below. | |More information on this Mission is available at the link shown below. | ||
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− | | 12 | + | | 12:20 |
| This is Ashwini Patil from IIT BombayA | | This is Ashwini Patil from IIT BombayA | ||
Thank You for watching. | Thank You for watching. | ||
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Revision as of 12:02, 23 June 2014
Time | Narration |
00:02 | Welcome to the spoken tutorial on Conditional statements in C and C++ |
00:08 | 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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00:16 | We will do this through examples.
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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.
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00:31 | 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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00:49 | It helps to make decision on, what code is to be executed.
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00:55 | We can check the conditions, whether true or false.
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01:00 | We can execute a single statement or a group of statements. |
01:07 | 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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01:49 | If condition2 is true, then statement3 will be executed.
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01:54 | And If condition2 is false, then statement2 will be executed |
02:02 | 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 |
02:18 | 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.
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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.
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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() function 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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03:10 | 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.
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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.
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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.
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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. |
07:43 | 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
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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++.
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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)
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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. |
Contributors and Content Editors
Ashwini, Devraj, Kavita salve, Krupali, PoojaMoolya, Priyacst, Sakinashaikh, Sandhya.np14, Sneha