Difference between revisions of "C-and-C++/C2/If-And-Else-If-statement/English-timed"

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|  Welcome to the spoken tutorial on '''Conditional statements in C and C++'''

|  Welcome to the spoken tutorial on '''Conditional statements in C and C++'''

|-

|-

|  In this tutorial we will learn,  

|  In this tutorial we will learn,  

|-

|-

| how to execute a single '''statement'''.

| how to execute a single '''statement'''.

|-

|-

| How to execute group of '''statements'''.

| How to execute group of '''statements'''.

|-

|-

| We will do this through examples.

| We will do this through examples.

|-

|-

| We will also see some common errors and their solutions.

| We will also see some common errors and their solutions.

|-

|-

|  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.

|-

|-

| '''gcc''' and '''g++ Compiler''' version 4.6.1  

| '''gcc''' and '''g++ Compiler''' version 4.6.1  

|-

|-

| Let us start with the Introduction to condition '''statements'''.  

| Let us start with the Introduction to condition '''statements'''.  

|-

|-

| A '''statement''' in a program controls the flow of program execution.

| A '''statement''' in a program controls the flow of program execution.

|-

|-

| It helps to make decision on, what code is to be executed.

| It helps to make decision on, what code is to be executed.

|-

|-

|We can check the conditions, whether true or false.

|We can check the conditions, whether true or false.

|-

|-

| We can execute a single statement or a group of statements.

| We can execute a single statement or a group of statements.

|-

|-

|  Let us understand the flow of if statements.

|  Let us understand the flow of if statements.

|-

|-

| Here, if the condition is true then , '''statement1''' will be executed.

| Here, if the condition is true then , '''statement1''' will be executed.

|-

|-

| If the condition is false then '''statement2''' will be executed.  

| If the condition is false then '''statement2''' will be executed.  

|-

|-

|  Now we will see the flow of else if '''statement''',

|  Now we will see the flow of else if '''statement''',

|-

|-

| Here, if '''condition1''' is true then '''statement1''' will be executed.

| Here, if '''condition1''' is true then '''statement1''' will be executed.

|-

|-

| 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'''.

|-

|-

| If '''condition2''' is true, then '''statement3''' will be executed.

| If '''condition2''' is true, then '''statement3''' will be executed.

|-

|-

| And If '''condition2''' is false, then '''statement2''' will be executed

| And If '''condition2''' is false, then '''statement2''' will be executed

|-

|-

|  Now Let us move on to our program.

|  Now Let us move on to our program.

|-

|-

| I have already typed the code on the editor.

| I have already typed the code on the editor.

|-

|-

| So let me open it.

| So let me open it.

|-

|-

| Note that our filename is '''ifstmt.c'''

| Note that our filename is '''ifstmt.c'''

|-

|-

| 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.

|-

|-

|  Let me explain the code now.  

|  Let me explain the code now.  

|-

|-

| This is our '''header file.'''

| This is our '''header file.'''

|-

|-

|  This is our '''main function.'''

|  This is our '''main function.'''

|-

|-

|  Here we have declared three integer '''variables''' '''a, b and sum.'''

|  Here we have declared three integer '''variables''' '''a, b and sum.'''

|-

|-

|  Here we are asking for user input.

|  Here we are asking for user input.

|-

|-

| User will enter the values of a and b.  

| User will enter the values of a and b.  

|-

|-

| The values will be stored in '''variable a''' and '''variable b.'''

| The values will be stored in '''variable a''' and '''variable b.'''

|-

|-

|The '''scanf()''' function reads data from the console.

|The '''scanf()''' function reads data from the console.

|-

|-

| It then stores the result in the given '''variable.'''

| It then stores the result in the given '''variable.'''

|-

|-

| 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.

|-

|-

| 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.

|-

|-

|  Here we add the values of''' a''' and '''b.'''

|  Here we add the values of''' a''' and '''b.'''

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|-

| We will store the result in '''sum.'''

| We will store the result in '''sum.'''

|-

|-

|  Then we print the result.

|  Then we print the result.

|-

|-

|  This is our '''if statement.'''  

|  This is our '''if statement.'''  

|-

|-

|Here, we check the condition whether '''sum''' is greater than 20.

|Here, we check the condition whether '''sum''' is greater than 20.

|-

|-

|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.

|-

|-

|  Now let me comment out  these lines.

|  Now let me comment out  these lines.

|-

|-

|This is our return statement.

|This is our return statement.

|-

|-

|  Now click on '''Save'''  

|  Now click on '''Save'''  

|-

|-

|First we will see the execution of if statement.

|First we will see the execution of if statement.

|-

|-

|  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.

|-

|-

|  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

|-

|-

|  To execute  type, '''./if''' press enter

|  To execute  type, '''./if''' press enter

|-

|-

|  it is displayed as,  

|  it is displayed as,  

|-

|-

|Enter the value of a and b.

|Enter the value of a and b.

|-

|-

|I will give the values as 10 and 12.

|I will give the values as 10 and 12.

|-

|-

|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.

|-

|-

|  Now come back to our program.

|  Now come back to our program.

|-

|-

|  We will check another condition.

|  We will check another condition.

|-

|-

|Let me remove the comment from here.

|Let me remove the comment from here.

|-

|-

|I will give the comment here.

|I will give the comment here.

|-

|-

|Now click on '''Save.'''

|Now click on '''Save.'''

|-

|-

|  This is our else-if statement.  

|  This is our else-if statement.  

|-

|-

|Here, we check another condition whether  '''Sum''' is greater than 10   

|Here, we check another condition whether  '''Sum''' is greater than 10   

|-

|-

|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.

|-

|-

|  Now come back to our terminal.

|  Now come back to our terminal.

|-

|-

|Let us compile as before.  

|Let us compile as before.  

|-

|-

|Let us execute as before.

|Let us execute as before.

|-

|-

| It is displayed as,

| It is displayed as,

|-

|-

|Enter the value of a and b.

|Enter the value of a and b.

|-

|-

| I will give the values as 10 and 2.

| I will give the values as 10 and 2.

|-

|-

|The output is displayed as: Sum of a and b is 12.  

|The output is displayed as: Sum of a and b is 12.  

|-

|-

|Sum is greater than 10 and less than 20.

|Sum is greater than 10 and less than 20.

|-

|-

|Let me clear the prompt.  

|Let me clear the prompt.  

|-

|-

| Now come back to our program.

| Now come back to our program.

|-

|-

|  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,

|-

|-

|  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.

|-

|-

|This is our else statement.

|This is our else statement.

|-

|-

| Now let us execute and see.  come back to our terminal.

| Now let us execute and see.  come back to our terminal.

|-

|-

|Let us compile as before. Let us execute as before.

|Let us compile as before. Let us execute as before.

|-

|-

|-

|-

|Enter the value of a and b.

|Enter the value of a and b.

|-

|-

|I will give the values as 3 and 5.

|I will give the values as 3 and 5.

|-

|-

| the output is as,  sum of a and b is 8.  

| the output is as,  sum of a and b is 8.  

|-

|-

|Sum is less than 10.

|Sum is less than 10.

|-

|-

|  Now we will see some common errors which we can come across.

|  Now we will see some common errors which we can come across.

|-

|-

|Come back to our program.

|Come back to our program.

|-

|-

| 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.

|-

|-

|Let see what will happen. Click on '''Save.'''

|Let see what will happen. Click on '''Save.'''

|-

|-

|  Let us execute. Come back to our terminal.

|  Let us execute. Come back to our terminal.

|-

|-

|Let us compile as before.  

|Let us compile as before.  

|-

|-

|  We see an error: else without a previous if

|  We see an error: else without a previous if

|-

|-

| Come back to our program.It is an syntax error.

| Come back to our program.It is an syntax error.

|-

|-

|If statement will never terminate with a semicolon.

|If statement will never terminate with a semicolon.

|-

|-

|And the else if statement will never work without an if.

|And the else if statement will never work without an if.

|-

|-

|  Let us fix the error. Delete the semicolon ; here

|  Let us fix the error. Delete the semicolon ; here

|-

|-

|  Now Click on '''Save.'''

|  Now Click on '''Save.'''

|-

|-

|  Let us execute. Come back to the terminal.

|  Let us execute. Come back to the terminal.

|-

|-

|  Let us compile as before. Let us execute as before.

|  Let us compile as before. Let us execute as before.

|-

|-

|Enter the value of a and b

|Enter the value of a and b

|-

|-

|I will give the values as 3 and 6.

|I will give the values as 3 and 6.

|-

|-

|The output is displayed as  

|The output is displayed as  

|-

|-

|Sum of a and b is 9. Sum is less than 10.

|Sum of a and b is 9. Sum is less than 10.

|-

|-

|-

|-

|Come back to our program.

|Come back to our program.

|-

|-

|  I will change a few things here.

|  I will change a few things here.

|-

|-

|  Press '''Shift, Ctrl and S'''  keys simultaneously on your keyboard.'''  

|  Press '''Shift, Ctrl and S'''  keys simultaneously on your keyboard.'''  

|-

|-

|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'''

|-

|-

|  We will change the header file as,  '''iostream'''

|  We will change the header file as,  '''iostream'''

|-

|-

|  Let us include the '''using '''statement here.

|  Let us include the '''using '''statement here.

|-

|-

|  Now click on the search for and  replace text option .  

|  Now click on the search for and  replace text option .  

|-

|-

|Let us replace the '''printf '''statement with the '''cout''' '''statement.'''

|Let us replace the '''printf '''statement with the '''cout''' '''statement.'''

|-

|-

|Click on '''Replace all''' and click on '''Close'''

|Click on '''Replace all''' and click on '''Close'''

|-

|-

|  Now delete the  closing brackets here.

|  Now delete the  closing brackets here.

|-

|-

|Replace the '''scanf''' statement with the '''cin''' statement.

|Replace the '''scanf''' statement with the '''cin''' statement.

|-

|-

|Type '''cin and two closing angle brackets >>'''

|Type '''cin and two closing angle brackets >>'''

|-

|-

|As we use '''cin >> function''' to read a line in C++.  

|As we use '''cin >> function''' to read a line in C++.  

   

   

|-

|-

| Now delete the '''format specifiers'''.

| Now delete the '''format specifiers'''.

|-

|-

|Delete the '''comma''' and '''ampersand''' &'''

|Delete the '''comma''' and '''ampersand''' &'''

|-

|-

|Delete the comma here and type two closing angle brackets.

|Delete the comma here and type two closing angle brackets.

|-

|-

|Again delete the '''ampersand'''and the closing brackets. Now Click on '''Save'''.

|Again delete the '''ampersand'''and the closing brackets. Now Click on '''Save'''.

|-

|-

|  Here delete the closing bracket and the comma.

|  Here delete the closing bracket and the comma.

|-

|-

|Now delete the ''''backslash n'''' and ''''format specifier'''

|Now delete the ''''backslash n'''' and ''''format specifier'''

'

'

|-

|-

| Now Type two opening brackets  

| Now Type two opening brackets  

|-

|-

|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”.'''

|-

|-

|Here also we will delete the closing bracket.

|Here also we will delete the closing bracket.

|-

|-

|Now again delete the closing bracket here and here.

|Now again delete the closing bracket here and here.

|-

|-

|Now    Click on '''Save'''

|Now    Click on '''Save'''

|-

|-

| Let us execute.

| Let us execute.

|-

|-

|| Come back to the terminal .Let me clear the prompt.

|| Come back to the terminal .Let me clear the prompt.

|-

|-

|To compile  type '''g++ space ifstmt.cpp space -o space if1'''

|To compile  type '''g++ space ifstmt.cpp space -o space if1'''

|-

|-

|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

|-

|-

|Now Press '''Enter'''

|Now Press '''Enter'''

|-

|-

|To execute type ./if1 and Press '''Enter'''

|To execute type ./if1 and Press '''Enter'''

|-

|-

|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.

|-

|-

|The output is displayed as,  Sum of a and b is '''30'''.

|The output is displayed as,  Sum of a and b is '''30'''.

|-

|-

|Sum is greater than 20.

|Sum is greater than 20.

|-

|-

|This brings us to the end of this tutorial.

|This brings us to the end of this tutorial.

|-

|-

|  Now come back to our slides.

|  Now come back to our slides.

|-

|-

|  Let us summarize.

|  Let us summarize.

|-

|-

|In this tutorial we learned, if statement eg. if(condition)

|In this tutorial we learned, if statement eg. if(condition)

|-

|-

| And else if statement eg. else if(condition)

| And else if statement eg. else if(condition)

|-

|-

|  As an assignment,  

|  As an assignment,  

|-

|-

|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.'''

|-

|-

|'''Hint: ''' use if statement.

|'''Hint: ''' use if statement.

|-

|-

|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.'''  

|-

|-

|'''Hint:''' use else-if statement.

|'''Hint:''' use else-if statement.

|-

|-

|  Watch the video available at the link shown below.  

|  Watch the video available at the link shown below.  

|-  

|-  

|It summarizes the Spoken Tutorial project.  

|It summarizes the Spoken Tutorial project.  

|-

|-

|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.

|-

|-

|| The Spoken Tutorial Project Team,

|| The Spoken Tutorial Project Team,

|-

|-

|Conducts workshops using spoken tutorials.  

|Conducts workshops using spoken tutorials.  

|-

|-

|Gives certificates to those who pass an online test.  

|Gives certificates to those who pass an online test.  

|-

|-

|For more details, please write to,  contact @ spoken hyphen tutorial dot org.

|For more details, please write to,  contact @ spoken hyphen tutorial dot org.

|-

|-

|  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.

|-

|-

|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.

|-

|-

|More information on this Mission is available at the link shown below.   

|More information on this Mission is available at the link shown below.   

|-

|-

| This is Ashwini Patil from IIT BombayA

| This is Ashwini Patil from IIT BombayA

Thank You for watching.

Thank You for watching.

|}

|}