Difference between revisions of "C-and-C++/C2/Tokens/English-timed"

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| Welcome to the spoken tutorial on '''Tokens-in-C-and-C-Plus-Plus''

| Welcome to the spoken tutorial on '''Tokens-in-C-and-C-Plus-Plus''

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|-

| In this tutorial we will learn ,

| In this tutorial we will learn ,

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|-

|How to define and use '''tokens.'''

|How to define and use '''tokens.'''

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|-

| We will do this with the help of an example.

| We will do this with the help of an example.

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|-

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

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

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|-

| To record this tutorial,

| To record this tutorial,

|-

|-

| I am using Ubuntu Operating system version 11.10

| I am using Ubuntu Operating system version 11.10

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|-

| gcc and g++ Compiler version 4.6.1.

| gcc and g++ Compiler version 4.6.1.

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|-

| Let us start with an introduction

| Let us start with an introduction

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|-

| Token is a generic word for '''Data types''', '''Variables''', '''Constants''' and '''Identifiers'''

| Token is a generic word for '''Data types''', '''Variables''', '''Constants''' and '''Identifiers'''

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|-

| Let us start with our program  

| Let us start with our program  

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|-

| I have already typed the code on the editor

| I have already typed the code on the editor

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|-

| Let me open it.  

| Let me open it.  

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|-

| Note that our file name is'' Tokens .c''.

| Note that our file name is'' Tokens .c''.

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|-

| In this program we will initialize the variables and print their values .

| In this program we will initialize the variables and print their values .

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|-

| Let me explain the code now.  

| Let me explain the code now.  

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|-

| This is our header file.

| This is our header file.

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|-

| This is our main functions.  

| This is our main functions.  

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|-

|Here,''' int '''is a '''keyword'''

|Here,''' int '''is a '''keyword'''

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|-

| The '''compiler''' knows the meaning of '''keywords'''.

| The '''compiler''' knows the meaning of '''keywords'''.

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| '''a''' is an integer '''variable'''  

| '''a''' is an integer '''variable'''  

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|-

| | We have assigned a value of '''2 '''to it.

| | We have assigned a value of '''2 '''to it.

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|-

| This is called as initialization.

| This is called as initialization.

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|-

|If a value is not assigned to a variable then it is called as declaration of the variable.  

|If a value is not assigned to a variable then it is called as declaration of the variable.  

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|-

| Here, b is a constant.

| Here, b is a constant.

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|-

| We have initialized b, by assigning a value of 4 to it.

| We have initialized b, by assigning a value of 4 to it.

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|-

| const keyword is used to create read only variable

| const keyword is used to create read only variable

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|-

| Let us switch back to our slides to know more about keywords and constant.  

| Let us switch back to our slides to know more about keywords and constant.  

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|-

| '''Keywords''' have fixed meanings that cannot be changed

| '''Keywords''' have fixed meanings that cannot be changed

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|-

| '''Keywords''' cannot be used as '''variable''' names

| '''Keywords''' cannot be used as '''variable''' names

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|-

| There are 32''' keywords''' in C

| There are 32''' keywords''' in C

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|-

| To name some, '''auto''', '''break''', '''case''', '''char''', '''enum''', '''extern''', etc.

| To name some, '''auto''', '''break''', '''case''', '''char''', '''enum''', '''extern''', etc.

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|-

|Constants, Constants are fixed values.

|Constants, Constants are fixed values.

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|-

| They do not change during the execution of a program.  

| They do not change during the execution of a program.  

|-

|-

| There are two types of constants , Numeric constants and Character constants.  

| There are two types of constants , Numeric constants and Character constants.  

|-

|-

| Now come back to our program.

| Now come back to our program.

|-

|-

|'Here, float is a data type of variable c.

|'Here, float is a data type of variable c.

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|-

| We have assigned it a value of , '''1.5'''

| We have assigned it a value of , '''1.5'''

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|-

| '''Data type '''is a finite set of values along with a set of rules

| '''Data type '''is a finite set of values along with a set of rules

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|-

| Here, '''d '''is a '''variable'''

| Here, '''d '''is a '''variable'''

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|-

| '''Char''' and single quotes suggest that we are dealing with a '''character'''

| '''Char''' and single quotes suggest that we are dealing with a '''character'''

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|-

| As a result, '''d''' is a '''character variable ''' storing the value ''''A''''

| As a result, '''d''' is a '''character variable ''' storing the value ''''A''''

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|-

| It is easy to see that '''int, double float''' and char are datatypes.  

| It is easy to see that '''int, double float''' and char are datatypes.  

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|-

| '''a,''' '''c and d''' are '''variables'''

| '''a,''' '''c and d''' are '''variables'''

|-

|-

| Now come back to our slides.

| Now come back to our slides.

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|-

|We will know more about datatypes and variable

|We will know more about datatypes and variable

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|-

|Data types: Let us begin with integer data type

|Data types: Let us begin with integer data type

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|-

|It is declared as int

|It is declared as int

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|-

| If we want to print an integer data type , we will use %d as the format specifier  

| If we want to print an integer data type , we will use %d as the format specifier  

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|-

| Similarly, we will use float and %f for floating point numbers

| Similarly, we will use float and %f for floating point numbers

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|-

|For character data type, we will  use char and %c

|For character data type, we will  use char and %c

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|-

| And For double data type, we will use double and %lf as the format specifier.

| And For double data type, we will use double and %lf as the format specifier.

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|-

| Now we will see the range of data types

| Now we will see the range of data types

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|-

| '''Integer''' data type has a range of this  

| '''Integer''' data type has a range of this  

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|-

| '''Floating point''' has a range of this  

| '''Floating point''' has a range of this  

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|-

| '''Character''' has a range of this

| '''Character''' has a range of this

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|-

| And '''Double''' has a range of this  

| And '''Double''' has a range of this  

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|-

|The values stored in the variable must not be greater or less than this range.  

|The values stored in the variable must not be greater or less than this range.  

|-

|-

| Now we will move on to variables.  

| Now we will move on to variables.  

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|-

| Variable is a data name.

| Variable is a data name.

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|-

|It may be used to store a data value .

|It may be used to store a data value .

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|-

|The values can change when a program runs.

|The values can change when a program runs.

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|-

| Before using a '''variable''' it must be declared

| Before using a '''variable''' it must be declared

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|-

| We should try to give meaningful names to '''variables'''

| We should try to give meaningful names to '''variables'''

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|-

| example '''john''', '''marks''', '''sum''' etc.  

| example '''john''', '''marks''', '''sum''' etc.  

|-

|-

| Now we will  move back to our program.

| Now we will  move back to our program.

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|-

| Here,''' printf''' is the '''identifier''' name for this function

| Here,''' printf''' is the '''identifier''' name for this function

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|-

| |Come back to our slides.

| |Come back to our slides.

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|-

|  Let us know about identifiers.

|  Let us know about identifiers.

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|-

| '''Identifiers''' are user defined names

| '''Identifiers''' are user defined names

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|-

| An '''identifier '''consists of letters and digits  

| An '''identifier '''consists of letters and digits  

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|-

| Both uppercase and lowercase letters are permitted  

| Both uppercase and lowercase letters are permitted  

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|-

| First character must be an alphabet or underscore .

| First character must be an alphabet or underscore .

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|-

|Now Come back to our program

|Now Come back to our program

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|-

|Here we have initialized the variables and constants.  

|Here we have initialized the variables and constants.  

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|-

|Here we print them.  

|Here we print them.  

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|-

|And this is our return statement.  

|And this is our return statement.  

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|-

|Now click on save.

|Now click on save.

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|-

| Let us execute the program

| Let us execute the program

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|-

| 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.

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|-

| To compile ,Type '''gcc space tokens dot c space hyphen o tok''' press''' Enter'''

| To compile ,Type '''gcc space tokens dot c space hyphen o tok''' press''' Enter'''

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|-

| To execute type'''./tok'''(dot slash tok)

| To execute type'''./tok'''(dot slash tok)

|-

|-

| The output is displayed.

| The output is displayed.

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|-

| We can see that here we have six values after the decimal point.

| We can see that here we have six values after the decimal point.

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|-

| And here we have two values.

| And here we have two values.

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|-

| Now let us find out how this happened. Come back to our program.

| Now let us find out how this happened. Come back to our program.

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|-

| This is because we have '''% point 2f''' here.

| This is because we have '''% point 2f''' here.

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|-

| It denotes that we can print only two values after the decimal point.

| It denotes that we can print only two values after the decimal point.

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|-

|  Suppose here I want an output with three decimal places.

|  Suppose here I want an output with three decimal places.

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|-

| Let us replace % point 2f with % point 3f

| Let us replace % point 2f with % point 3f

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|-

| Now Click on '''Save'''

| Now Click on '''Save'''

|-

|-

| Come back to our terminal.

| Come back to our terminal.

|-

|-

|  Compile as before, execute as before.

|  Compile as before, execute as before.

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|-

|We see here three values after the decimal point.  

|We see here three values after the decimal point.  

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|-

|Now we will execute the same program in c++  

|Now we will execute the same program in c++  

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|-

| Come back to our program

| Come back to our program

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|-

| I will change a few things here

| I will change a few things here

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|-

| First press shift+ctrl+s keys simultaneously on your keyboard.

| First press shift+ctrl+s keys simultaneously on your keyboard.

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|-

| Now save the file with an extension .cpp and click on save  

| Now save the file with an extension .cpp and click on save  

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|-

|let us change the header file as iostream

|let us change the header file as iostream

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|-

| Now  include the '''using '''statement   

| Now  include the '''using '''statement   

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|-

| And click on Save.

| And click on Save.

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|-

|Now replace the '''printf '''statement with the  '''cout'''  statement

|Now replace the '''printf '''statement with the  '''cout'''  statement

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|-

| Since we use ''cout<< function''' to print a line in C++

| Since we use ''cout<< function''' to print a line in C++

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|-

| Click on Search for and replace text option  

| Click on Search for and replace text option  

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|-

| Type here printf opening bracket “(”  

| Type here printf opening bracket “(”  

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|-

| And here in this column type, cout and two opening angle brackets “<<”.  

| And here in this column type, cout and two opening angle brackets “<<”.  

|-

|-

| Now click on Replace All  and click on Close.

| Now click on Replace All  and click on Close.

|-

|-

| We don't need the '''format specifier''' and /n  

| We don't need the '''format specifier''' and /n  

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|-

| Let us delete them.  

| Let us delete them.  

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|-

| Now delete the comma and  type two opening angle brackets.

| Now delete the comma and  type two opening angle brackets.

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|-

|Click on Save. Now delete the closing bracket  

|Click on Save. Now delete the closing bracket  

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|-

| Type two opening angle brackets again.  

| Type two opening angle brackets again.  

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|-

| And within the double quotes type \n.  

| And within the double quotes type \n.  

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|-

| Now Click on Save

| Now Click on Save

|-

|-

|Let us execute the program. Come back to our terminal.

|Let us execute the program. Come back to our terminal.

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|-

|To compile , type g++ space  tokens dot cpp space  hyphen o space tok 1

|To compile , type g++ space  tokens dot cpp space  hyphen o space tok 1

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|-

| Here we have tok1 because we don't want to overwrite the output parameter tok for the file tokens.c  

| Here we have tok1 because we don't want to overwrite the output parameter tok for the file tokens.c  

|-

|-

| Now press Enter

| Now press Enter

|-

|-

| To execute.Type ./tok1 . Press Enter  

| To execute.Type ./tok1 . Press Enter  

|-

|-

| The output is displayed.

| The output is displayed.

|-

|-

| Now let us move on to some common errors which we can come across.  

| Now let us move on to some common errors which we can come across.  

|-

|-

| Come back to our program.

| Come back to our program.

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|-

|  Suppose here I will reassign a new value to b as 8.

|  Suppose here I will reassign a new value to b as 8.

|-

|-

| Now Click on Save. Let us see what happens.

| Now Click on Save. Let us see what happens.

|-

|-

| Come back to our terminal.  

| Come back to our terminal.  

|-

|-

| Let me clear the prompt.

| Let me clear the prompt.

|-

|-

| Now compile as before.

| Now compile as before.

|-

|-

| We see an error at line no.7 in our tokens. cpp file.

| We see an error at line no.7 in our tokens. cpp file.

|-

|-

| Assignment of read only variable b.   

| Assignment of read only variable b.   

|-

|-

|Come back to our program

|Come back to our program

|-

|-

| This is because b is a constant. Constants are  fixed values.

| This is because b is a constant. Constants are  fixed values.

|-

|-

|They do not change during the execution of program.

|They do not change during the execution of program.

|-

|-

| Hence it is giving an error. Let us fix the error.

| Hence it is giving an error. Let us fix the error.

|-

|-

|Delete this. Click on Save

|Delete this. Click on Save

|-

|-

| Let us execute again. Come back to our terminal

| Let us execute again. Come back to our terminal

|-

|-

|Compile as before.  

|Compile as before.  

|-

|-

|Execute as before. Yes it is working.

|Execute as before. Yes it is working.

|-

|-

| Now we will see another common error.

| Now we will see another common error.

|-

|-

|Switch back to our program.

|Switch back to our program.

|-

|-

| Suppose here I will miss the single quotes. Click on Save

| Suppose here I will miss the single quotes. Click on Save

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|-

| let us execute. Come back to our  terminal.

| let us execute. Come back to our  terminal.

|-

|-

|Compile as before.

|Compile as before.

|-

|-

| we see an error at line no.9 in our tokens dot cpp file.

| we see an error at line no.9 in our tokens dot cpp file.

|-

|-

|A was not declared in the scope. Come back to our program.

|A was not declared in the scope. Come back to our program.

|-

|-

| This is because anything within the single quotes is considered as a character value.  

| This is because anything within the single quotes is considered as a character value.  

|-

|-

| And here we have declared d as a character variable.

| And here we have declared d as a character variable.

|-

|-

| Let us fix the error. Type single quotes at line no.9 here.

| Let us fix the error. Type single quotes at line no.9 here.

|-

|-

|Now Click on Save . Let us execute .

|Now Click on Save . Let us execute .

|-

|-

|Come back to our terminal  

|Come back to our terminal  

|-

|-

|Now Compile as before  

|Now Compile as before  

|-

|-

|Execute as before. Yes it is working.  

|Execute as before. Yes it is working.  

|-

|-

|Now  switch back to our slides.  

|Now  switch back to our slides.  

|-

|-

| Let us summarize  

| Let us summarize  

|-

|-

| In this tutorial we learnt,  

| In this tutorial we learnt,  

|-

|-

| Data types eg. int, double, float etc.  

| Data types eg. int, double, float etc.  

|-

|-

| Variables eg. int a=2;  

| Variables eg. int a=2;  

|-

|-

| Identifiers eg. printf() and

| Identifiers eg. printf() and

|-  

|-  

| Constant eg. double const b=4;  

| Constant eg. double const b=4;  

|-

|-

| As an assignment

| As an assignment

|-

|-

| Write a  program to calculate the simple interest.

| Write a  program to calculate the simple interest.

|-

|-

| Hint:  principal * rate * time upon  100

| Hint:  principal * rate * time upon  100

|-

|-

|Watch the video available at the link shown below

|Watch the video available at the link shown below

|-

|-

| It summarises the Spoken Tutorial project  

| It summarises 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-tutorial.org

| For more details,please write to contact @spoken-tutorial.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

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|-

| Ashwini Patil from IIT Bombay signing off .Thank You for joining

| Ashwini Patil from IIT Bombay signing off .Thank You for joining

|}

|}