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

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|-
 
|-
 
| 00:01  
 
| 00:01  
−
| 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'''.
  
 
|-
 
|-
−
|00:06
+
| 00:06
 
| In this tutorial we will learn ,
 
| In this tutorial we will learn ,
  
 
|-
 
|-
−
|00:09
+
| 00:09
−
|How to define and use '''tokens.'''
+
| How to define and use '''tokens.'''
  
 
|-
 
|-
−
|00:12
+
| 00:12
−
| We will do this with the help of an example.
+
|We will do this with the help of an example.
  
 
|-
 
|-
−
|00:15
+
| 00:15
 
| We will also see some common errors and their solutions.
 
| We will also see some common errors and their solutions.
  
 
|-
 
|-
 
| 00:20
 
| 00:20
−
| To record this tutorial,
+
| To record this tutorial, I am using '''Ubuntu Operating system version 11.10''',
−
|-
+
−
|00:21
+
−
| I am using Ubuntu Operating system version 11.10
+
  
 
|-
 
|-
−
|00:26
+
| 00:26
−
| gcc and g++ Compiler version 4.6.1.
+
| '''gcc and g++ Compiler version 4.6.1'''.
  
 
|-
 
|-
−
|00:33
+
| 00:33
−
| Let us start with an introduction
+
| Let us start with an introduction.
  
 
|-
 
|-
−
|00:36
+
| 00:36
−
| Token is a generic word for '''Data types''', '''Variables''', '''Constants''' and '''Identifiers'''
+
| Token is a generic word for '''data types''', '''variables''', '''constants''' and '''identifiers'''.
  
 
|-
 
|-
−
|00:46
+
| 00:46
−
| Let us start with our program  
+
| Let us start with our program.
 +
 
 
|-
 
|-
−
|00:49
+
| 00:49
−
| I have already typed the code on the editor
+
| I have already typed the code on the editor.
  
 
|-
 
|-
−
|00:53
+
| 00:53
 
| Let me open it.  
 
| Let me open it.  
  
 
|-
 
|-
−
|00:56
+
| 00:56
−
| Note that our file name is'' Tokens .c''.
+
| Note that our file name is 'tokens.c'.
  
 
|-
 
|-
−
|01:04
+
| 01:04
−
| In this program we will initialize the variables and print their values .
+
| In this program we will initialize the variables and print their values.
  
 
|-
 
|-
−
|01:09
+
| 01:09
 
| Let me explain the code now.  
 
| Let me explain the code now.  
  
 
|-
 
|-
−
|01:12
+
| 01:12
 
| This is our header file.
 
| This is our header file.
  
 
|-
 
|-
−
|01:16
+
| 01:16
−
| This is our main functions.  
+
| This is our main function.  
  
 
|-
 
|-
 
| 01:20
 
| 01:20
−
|Here,''' int '''is a '''keyword'''
+
| Here,''' int '''is a '''keyword'''.
  
 
|-
 
|-
−
|01:22
+
| 01:22
−
| The '''compiler''' knows the meaning of '''keywords'''.
+
| The '''compiler''' knows the meaning of '''keyword'''.
  
 
|-
 
|-
 
| 01:26
 
| 01:26
−
| '''a''' is an integer '''variable'''  
+
| '''a''' is an integer '''variable'''.
  
 
|-
 
|-
 
| 01:28
 
| 01:28
−
| | We have assigned a value of '''2 '''to it.
+
| We have assigned a value of '''2 '''to it.
  
 
|-
 
|-
−
|01:32
+
| 01:32
 
| This is called as initialization.
 
| This is called as initialization.
  
 
|-
 
|-
 
| 01:35
 
| 01:35
−
|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.  
  
 
|-
 
|-
−
|01:43
+
| 01:43
−
| Here, b is a constant.
+
| Here, '''b''' is a '''constant'''.
  
 
|-
 
|-
 
| 01:46
 
| 01:46
−
| We have initialized b, by assigning a value of 4 to it.
+
| We have initialized 'b' by assigning a value of 4 to it.
  
 
|-
 
|-
−
|01:53
+
| 01:53
−
| const keyword is used to create read only variable
+
| '''const''' keyword is used to create 'read only' variable.
  
 
|-
 
|-
−
|01:58
+
| 01:58
 
| 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.  
  
 
|-
 
|-
 
| 02:06
 
| 02:06
−
| '''Keywords''' have fixed meanings that cannot be changed
+
| '''Keywords''' have fixed meanings that cannot be changed.
  
 
|-
 
|-
−
|02:11
+
| 02:11
−
| '''Keywords''' cannot be used as '''variable''' names
+
| '''Keywords''' cannot be used as '''variable''' names.
  
 
|-
 
|-
−
|02:15
+
| 02:15
−
| There are 32''' keywords''' in C
+
| There are 32''' keywords''' in C.
  
 
|-
 
|-
−
|02:18
+
| 02:18
 
| To name some, '''auto''', '''break''', '''case''', '''char''', '''enum''', '''extern''', etc.
 
| To name some, '''auto''', '''break''', '''case''', '''char''', '''enum''', '''extern''', etc.
  
 
|-
 
|-
 
| 02:28
 
| 02:28
−
|Constants, Constants are fixed values.
+
| Constants: constants are fixed values.
  
 
|-
 
|-
−
|02:33
+
| 02:33
 
| They do not change during the execution of a program.  
 
| They do not change during the execution of a program.  
  
 
|-
 
|-
−
|02:38
+
| 02:38
−
| There are two types of constants , Numeric constants and Character constants.  
+
| There are two types of constants, Numeric constants and Character constants.  
  
 
|-
 
|-
−
|02:45
+
| 02:45
 
| Now come back to our program.
 
| Now come back to our program.
  
 
|-
 
|-
 
| 02:47
 
| 02:47
−
|'Here, float is a data type of variable c.
+
| Here, '''float''' is a data type of variable '''c'''.
  
 
|-
 
|-
−
|02:52
+
| 02:52
−
| We have assigned it a value of , '''1.5'''
+
| We have assigned it a value of '''1.5'''.
  
 
|-
 
|-
−
|02:56
+
| 02:56
−
| '''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.
  
 
|-
 
|-
 
| 03:04
 
| 03:04
−
| Here, '''d '''is a '''variable'''
+
| Here, '''d '''is a '''variable'''.
  
 
|-
 
|-
−
|03:07
+
| 03:07
−
| '''Char''' and single quotes suggest that we are dealing with a '''character'''
+
| '''char''' and single quotes suggest that we are dealing with a '''character'''.
  
 
|-
 
|-
−
|03:12
+
| 03:12
−
| As a result, '''d''' is a '''character variable ''' storing the value ''''A''''
+
| As a result, '''d''' is a '''character variable ''' storing the value '''A'''.
  
 
|-
 
|-
 
| 03:20
 
| 03:20
−
| 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 data types.  
  
 
|-
 
|-
−
|03:30
+
| 03:30
−
| '''a,''' '''c and d''' are '''variables'''
+
| '''a,''' '''c''' and '''d''' are '''variables'''.
  
 
|-
 
|-
−
|03:35
+
| 03:35
 
| Now come back to our slides.
 
| Now come back to our slides.
  
 
|-
 
|-
 
| 03:37
 
| 03:37
−
|We will know more about datatypes and variable
+
| We will know more about data types and variables.
  
 
|-
 
|-
−
|03:48
+
| 03:48
−
|Data types: Let us begin with integer data type
+
| Data types: Let us begin with integer data type.
  
 
|-
 
|-
−
|03:50
+
| 03:50
−
|It is declared as int
+
| It is declared as '''int'''.
 +
 
 
|-
 
|-
−
|03:53
+
| 03:53
−
| 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.
  
 
|-
 
|-
 
| 04:01
 
| 04:01
−
| Similarly, we will use float and %f for floating point numbers
+
| Similarly, we will use '''float''' and '''%f''' for floating point numbers.
  
 
|-
 
|-
−
|04:09
+
| 04:09
−
|For character data type, we will  use char and %c
+
| For character data type, we will  use '''char''' and '''%c'''.
  
 
|-
 
|-
−
|04:15
+
| 04:15
−
| 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.
 +
 
 
|-
 
|-
−
|04:24
+
| 04:24
−
| Now we will see the range of data types
+
| Now we will see the range of data types.
  
 
|-
 
|-
−
|04:29
+
| 04:29
 
| '''Integer''' data type has a range of this  
 
| '''Integer''' data type has a range of this  
  
 
|-
 
|-
−
|04:34
+
| 04:34
 
| '''Floating point''' has a range of this  
 
| '''Floating point''' has a range of this  
  
 
|-
 
|-
−
|04:39
+
| 04:39
 
| '''Character''' has a range of this
 
| '''Character''' has a range of this
  
 
|-
 
|-
−
|04:42
+
| 04:42
 
| And '''Double''' has a range of this  
 
| And '''Double''' has a range of this  
  
 
|-
 
|-
 
| 04:47
 
| 04:47
−
|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.  
  
 
|-
 
|-
−
|04:56
+
| 04:56
 
| Now we will move on to variables.  
 
| Now we will move on to variables.  
  
 
|-
 
|-
−
|05:00
+
| 05:00
 
| Variable is a data name.
 
| Variable is a data name.
  
 
|-
 
|-
−
|05:02
+
| 05:02
−
|It may be used to store a data value .
+
| It may be used to store a data value .
  
 
|-
 
|-
−
|05:06
+
| 05:06
−
|The values can change when a program runs.
+
| The values can change when a program runs.
 +
 
 
|-
 
|-
−
|05:10
+
| 05:10
−
| Before using a '''variable''' it must be declared
+
| Before using a variable it must be declared.
  
 
|-
 
|-
−
|05:14
+
| 05:14
−
| We should try to give meaningful names to '''variables'''
+
| We should try to give meaningful names to variables.
  
 
|-
 
|-
−
|05:18
+
| 05:18
 
| example '''john''', '''marks''', '''sum''' etc.  
 
| example '''john''', '''marks''', '''sum''' etc.  
  
 
|-
 
|-
−
|05:24
+
| 05:24
−
| Now we will move back to our program.
+
| Now we will move back to our program.
  
 
|-
 
|-
 
| 05:27
 
| 05:27
−
| Here,''' printf''' is the '''identifier''' name for this function
+
| Here,''' printf''' is the '''identifier''' name for this function.
−
 
+
−
 
+
  
 
|-
 
|-
 
| 05:32
 
| 05:32
−
| |Come back to our slides.
+
|Come back to our slides.
  
 
|-
 
|-
 
| 05:35
 
| 05:35
−
| Let us know about identifiers.
+
| Let us know about identifiers.
  
 
|-
 
|-
 
| 05:38
 
| 05:38
−
| '''Identifiers''' are user defined names
+
| '''Identifiers''' are user defined names.
  
 
|-
 
|-
−
|05:41
+
| 05:41
−
| An '''identifier '''consists of letters and digits  
+
| An '''identifier '''consists of letters and digits.
  
 
|-
 
|-
−
|05:46
+
| 05:46
−
| Both uppercase and lowercase letters are permitted  
+
| Both uppercase and lowercase letters are permitted.
  
 
|-
 
|-
−
|05:51
+
| 05:51
−
| First character must be an alphabet or underscore .
+
| First character must be an alphabet or underscore.
  
 
|-
 
|-
 
| 05:55
 
| 05:55
−
|Now Come back to our program
+
| Now Come back to our program.
  
 
|-
 
|-
 
| 05:58
 
| 05:58
−
|Here we have initialized the variables and constants.  
+
| Here we have initialized the variables and constants.  
  
 
|-
 
|-
 
| 06:02
 
| 06:02
−
|Here we print them.  
+
| Here we print them.  
  
 
|-
 
|-
 
| 06:05
 
| 06:05
−
|And this is our return statement.  
+
| And this is our return statement.  
  
 
|-
 
|-
 
| 06:08
 
| 06:08
−
|Now click on save.
+
| Now click on Save.
  
 
|-
 
|-
 
| 06:10
 
| 06:10
−
| Let us execute the program
+
| Let us execute the program.
  
 
|-
 
|-
−
|06:12
+
| 06:12
−
| 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.
  
 
|-
 
|-
−
|06:21  
+
| 06:21  
−
| 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.
  
 
|-
 
|-
 
| 06:30
 
| 06:30
−
| To execute type'''./tok'''(dot slash tok)
+
| To execute, type '''./tok''' (dot slash tok).
  
 
|-
 
|-
Line 332: Line 331:
  
 
|-
 
|-
−
|06:39
+
| 06:39
 
| 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.
  
 
|-
 
|-
−
|06:44
+
| 06:44
 
| And here we have two values.
 
| And here we have two values.
  
Line 348: Line 347:
  
 
|-
 
|-
−
|06:59
+
| 06:59
 
| 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.
−
 
  
 
|-
 
|-
 
| 07:04
 
| 07:04
−
| Suppose here I want an output with three decimal places.
+
| Suppose here I want an output with three decimal places.
  
 
|-
 
|-
 
| 07:09
 
| 07:09
−
| Let us replace % point 2f with % point 3f
+
| Let us replace % point 2f with % point 3f.
  
 
|-
 
|-
−
|07:16
+
| 07:16
−
| Now Click on '''Save'''
+
| Now click on Save.
  
 
|-
 
|-
−
|07:19
+
| 07:19
 
| Come back to our terminal.
 
| Come back to our terminal.
  
 
|-
 
|-
−
|07:22
+
| 07:22
−
| Compile as before, execute as before.
+
| Compile as before, execute as before.
  
 
|-
 
|-
 
| 07:28
 
| 07:28
−
|We see here three values after the decimal point.  
+
| We see here three values after the decimal point.  
  
 
|-
 
|-
−
|07:33
+
| 07:33
−
|Now we will execute the same program in c++  
+
| Now we will execute the same program in c++.
−
 
+
  
 
|-
 
|-
−
|07:36
+
| 07:36
−
| Come back to our program
+
| Come back to our program.
  
 
|-
 
|-
 
| 07:40
 
| 07:40
−
| I will change a few things here
+
| I will change a few things here.
  
 
|-
 
|-
 
| 07:42
 
| 07:42
−
| First press shift+ctrl+s keys simultaneously on your keyboard.
+
| First press '''Shift+Ctrl+s''' keys simultaneously on your keyboard.
  
 
|-
 
|-
 
| 07:50
 
| 07:50
−
| Now save the file with an extension .cpp and click on save
+
| Now save the file with an extension '''.cpp''' and click on Save.
 +
 
 
|-
 
|-
 
| 07:58
 
| 07:58
−
|let us change the header file as iostream
+
| Let us change the header file as '''iostream'''
 +
 
 
|-
 
|-
 
| 08:03
 
| 08:03
−
| Now  include the '''using '''statement   
+
| Now  include the '''using '''statement.  
  
 
|-
 
|-
 
| 08:08
 
| 08:08
 
| And click on Save.
 
| And click on Save.
−
 
  
 
|-
 
|-
 
| 08:11
 
| 08:11
−
|Now replace the '''printf '''statement with the  '''cout'''  statement
+
| Now replace the '''printf '''statement with the  '''cout'''  statement  
  
 
|-
 
|-
−
|08:15
+
| 08:15
−
| Since we use ''cout<< function''' to print a line in C++
+
| since we use '''cout<<''' function to print a line in C++.
 +
 
 
|-
 
|-
 
| 08:21
 
| 08:21
−
| Click on Search for and replace text option  
+
| Click on Search for and replace text option.
  
 
|-
 
|-
 
| 08:27
 
| 08:27
 
| Type here printf opening bracket “(”  
 
| Type here printf opening bracket “(”  
 +
 
|-
 
|-
 
| 08:33
 
| 08:33
 
| And here in this column type, cout and two opening angle brackets “<<”.  
 
| And here in this column type, cout and two opening angle brackets “<<”.  
 +
 
|-
 
|-
 
| 08:40
 
| 08:40
Line 431: Line 432:
 
|-
 
|-
 
| 08:45
 
| 08:45
−
| We don't need the '''format specifier''' and /n  
+
| We don't need the '''format specifier''' and '\n'
  
 
|-
 
|-
−
|08:50
+
| 08:50
 
| Let us delete them.  
 
| Let us delete them.  
  
 
|-
 
|-
−
|08:52
+
| 08:52
 
| Now delete the comma and  type two opening angle brackets.
 
| Now delete the comma and  type two opening angle brackets.
−
 
  
 
|-
 
|-
 
| 09:01
 
| 09:01
−
|Click on Save. Now delete the closing bracket  
+
|Click on Save. Now delete the closing bracket.
−
 
+
  
 
|-
 
|-
−
|09:04
+
| 09:04
 
| Type two opening angle brackets again.  
 
| Type two opening angle brackets again.  
−
 
  
 
|-
 
|-
−
|09:09
+
| 09:09
 
| And within the double quotes type \n.  
 
| And within the double quotes type \n.  
  
 
|-
 
|-
−
|09:16
+
| 09:16
−
| Now Click on Save
+
| Now Click on Save.
−
 
+
  
 
|-
 
|-
−
|09:20
+
| 09:20
−
|Let us execute the program. Come back to our terminal.
+
| Let us execute the program. Come back to our terminal.
  
 
|-
 
|-
 
| 09:24
 
| 09:24
−
|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 tok1'''.
  
 +
|-
 +
| 09:35
 +
| Here we have '''tok1''' because we don't want to overwrite the output parameter tok for the file tokens.c.
  
 
|-
 
|-
−
|09:35
+
| 09:46
−
| Here we have tok1 because we don't want to overwrite the output parameter tok for the file tokens.c
+
| Now press Enter.
  
 
|-
 
|-
−
|09:46
+
| 09:48
−
| Now press Enter
+
| To execute, type '''./tok1''' . Press Enter.
  
−
|-
 
−
|09:48
 
−
| To execute.Type ./tok1 . Press Enter
 
 
|-
 
|-
 
| 09:55
 
| 09:55
 
| The output is displayed.
 
| The output is displayed.
−
 
  
 
|-
 
|-
−
|09:59
+
| 09:59
 
| 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.  
  
 
|-
 
|-
−
|10:03
+
| 10:03
 
| Come back to our program.
 
| Come back to our program.
  
 
|-
 
|-
−
|10:05
+
| 10:05
−
| Suppose here I will reassign a new value to b as 8.
+
| Suppose here I will reassign a new value to b as 8.
  
 
|-
 
|-
−
|10:12
+
| 10:12
−
| Now Click on Save. Let us see what happens.
+
| Now click on Save. Let us see what happens.
  
 
|-
 
|-
Line 520: Line 516:
 
|-
 
|-
 
| 10:32
 
| 10:32
−
| Assignment of read only variable b.   
+
| "Assignment of read only variable 'b' ".   
  
 
|-
 
|-
 
|10:36
 
|10:36
−
|Come back to our program
+
|Come back to our program.
 +
 
 
|-
 
|-
 
| 10:39
 
| 10:39
−
| This is because b is a constant. Constants are  fixed values.
+
| This is because 'b' is a constant. Constants are  fixed values.
 +
 
 
|-
 
|-
 
|10:45
 
|10:45
Line 538: Line 536:
 
|-
 
|-
 
| 10:54
 
| 10:54
−
|Delete this. Click on Save
+
|Delete this. Click on Save.
  
 
|-
 
|-
 
| 10:57
 
| 10:57
−
| Let us execute again. Come back to our terminal
+
| Let us execute again. Come back to our terminal.
  
 
|-
 
|-
Line 550: Line 548:
 
|-
 
|-
 
| 11:03
 
| 11:03
−
|Execute as before. Yes it is working.
+
|Execute as before. Yes, it is working.
  
 
|-
 
|-
Line 562: Line 560:
 
|-
 
|-
 
|11:15
 
|11:15
−
| Suppose here I will miss the single quotes. Click on Save
+
| Suppose here I will miss the single quotes. Click on Save.
  
 
|-
 
|-
 
| 11:21
 
| 11:21
−
| let us execute. Come back to our  terminal.
+
| Let us execute. Come back to our  terminal.
  
 
|-
 
|-
Line 574: Line 572:
 
|-
 
|-
 
| 11:28
 
| 11:28
−
| 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.
  
 
|-
 
|-
−
|11:34
+
| 11:34
−
|A was not declared in the scope. Come back to our program.
+
| " 'A' was not declared in the scope". Come back to our program.
  
 
|-
 
|-
Line 586: Line 584:
 
|-
 
|-
 
|11:47
 
|11:47
−
| And here we have declared d as a character variable.
+
| And here we have declared 'd' as a character variable.
  
 
|-
 
|-
Line 594: Line 592:
 
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|Now Click on Save . Let us execute .
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|Now Click on Save. Let us execute.
  
 
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|12:02
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|Come back to our terminal.
  
 
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|12:15
 
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| Let us summarize  
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|Let us summarize.In this tutorial we learnt,  
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| Identifiers eg. printf() and
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|12:41
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| Write a  program to calculate the simple interest.
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|12:45
 
|12:45
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| Hint: principal * rate * time upon  100
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| Hint: principal * rate * time upon  100.
  
 
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|12:50
 
|12:50
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|Watch the video available at the link shown below
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|Watch the video available at the link shown below.
  
 
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| It summarises the Spoken Tutorial project  
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| The Spoken Tutorial Project Team  
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| The Spoken Tutorial Project Team:
  
 
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|13:03
 
|13:03
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| Conducts workshops using spoken tutorials  
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| Conducts workshops using spoken tutorials,
  
 
|-
 
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|13:07
 
|13:07
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| Gives certificates to those who pass an online test  
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| Gives certificates to those who pass an online test.
  
 
|-
 
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|13:10
 
|13:10
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| For more details,please write to contact @spoken-tutorial.org
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| For more details, please write to contact @spoken-tutorial.org
  
 
|-
 
|-
 
| 13:19
 
| 13:19
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| Spoken Tutorial Project is a part of the Talk to a Teacher project
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| Spoken Tutorial Project is a part of the Talk to a Teacher project.
 
   
 
   
 
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|13:24
 
|13:24
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| It is supported by the National Mission on Education through ICT, MHRD, Government of India
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| It is supported by the National Mission on Education through ICT, MHRD, Government of India.
  
 
|-
 
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|13:30
 
|13:30
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| More information on this Mission is available at the link  shown below
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| More information on this Mission is available at the link  shown below.
  
 
|-
 
|-
 
|13:35
 
|13:35
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| Ashwini Patil from IIT Bombay signing off .Thank You for joining
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| Ashwini Patil from IIT Bombay signing off .Thank You for joining.
  
 
|}
 
|}

Latest revision as of 16:24, 22 March 2017

Time Narration
00:01 Welcome to the spoken tutorial on Tokens in C and C Plus Plus.
00:06 In this tutorial we will learn ,
00:09 How to define and use tokens.
00:12 We will do this with the help of an example.
00:15 We will also see some common errors and their solutions.
00:20 To record this tutorial, I am using Ubuntu Operating system version 11.10,
00:26 gcc and g++ Compiler version 4.6.1.
00:33 Let us start with an introduction.
00:36 Token is a generic word for data types, variables, constants and identifiers.
00:46 Let us start with our program.
00:49 I have already typed the code on the editor.
00:53 Let me open it.
00:56 Note that our file name is 'tokens.c'.
01:04 In this program we will initialize the variables and print their values.
01:09 Let me explain the code now.
01:12 This is our header file.
01:16 This is our main function.
01:20 Here, int is a keyword.
01:22 The compiler knows the meaning of keyword.
01:26 a is an integer variable.
01:28 We have assigned a value of 2 to it.
01:32 This is called as initialization.
01:35 If a value is not assigned to a variable then it is called as declaration of the variable.
01:43 Here, b is a constant.
01:46 We have initialized 'b' by assigning a value of 4 to it.
01:53 const keyword is used to create 'read only' variable.
01:58 Let us switch back to our slides to know more about keywords and constant.
02:06 Keywords have fixed meanings that cannot be changed.
02:11 Keywords cannot be used as variable names.
02:15 There are 32 keywords in C.
02:18 To name some, auto, break, case, char, enum, extern, etc.
02:28 Constants: constants are fixed values.
02:33 They do not change during the execution of a program.
02:38 There are two types of constants, Numeric constants and Character constants.
02:45 Now come back to our program.
02:47 Here, float is a data type of variable c.
02:52 We have assigned it a value of 1.5.
02:56 Data type is a finite set of values along with a set of rules.
03:04 Here, d is a variable.
03:07 char and single quotes suggest that we are dealing with a character.
03:12 As a result, d is a character variable storing the value A.
03:20 It is easy to see that int, double, float and char are data types.
03:30 a, c and d are variables.
03:35 Now come back to our slides.
03:37 We will know more about data types and variables.
03:48 Data types: Let us begin with integer data type.
03:50 It is declared as int.
03:53 If we want to print an integer data type , we will use %d as the format specifier.
04:01 Similarly, we will use float and %f for floating point numbers.
04:09 For character data type, we will use char and %c.
04:15 And For double data type, we will use double and %lf as the format specifier.
04:24 Now we will see the range of data types.
04:29 Integer data type has a range of this
04:34 Floating point has a range of this
04:39 Character has a range of this
04:42 And Double has a range of this
04:47 The values stored in the variable must not be greater or less than this range.
04:56 Now we will move on to variables.
05:00 Variable is a data name.
05:02 It may be used to store a data value .
05:06 The values can change when a program runs.
05:10 Before using a variable it must be declared.
05:14 We should try to give meaningful names to variables.
05:18 example john, marks, sum etc.
05:24 Now we will move back to our program.
05:27 Here, printf is the identifier name for this function.
05:32 Come back to our slides.
05:35 Let us know about identifiers.
05:38 Identifiers are user defined names.
05:41 An identifier consists of letters and digits.
05:46 Both uppercase and lowercase letters are permitted.
05:51 First character must be an alphabet or underscore.
05:55 Now Come back to our program.
05:58 Here we have initialized the variables and constants.
06:02 Here we print them.
06:05 And this is our return statement.
06:08 Now click on Save.
06:10 Let us execute the program.
06:12 Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
06:21 To compile, type gcc space tokens dot c space hyphen o tok. Press Enter.
06:30 To execute, type ./tok (dot slash tok).
06:35 The output is displayed.
06:39 We can see that here we have six values after the decimal point.
06:44 And here we have two values.
06:48 Now let us find out how this happened. Come back to our program.
06:54 This is because we have % point 2f here.
06:59 It denotes that we can print only two values after the decimal point.
07:04 Suppose here I want an output with three decimal places.
07:09 Let us replace % point 2f with % point 3f.
07:16 Now click on Save.
07:19 Come back to our terminal.
07:22 Compile as before, execute as before.
07:28 We see here three values after the decimal point.
07:33 Now we will execute the same program in c++.
07:36 Come back to our program.
07:40 I will change a few things here.
07:42 First press Shift+Ctrl+s keys simultaneously on your keyboard.
07:50 Now save the file with an extension .cpp and click on Save.
07:58 Let us change the header file as iostream
08:03 Now include the using statement.
08:08 And click on Save.
08:11 Now replace the printf statement with the cout statement
08:15 since we use cout<< function to print a line in C++.
08:21 Click on Search for and replace text option.
08:27 Type here printf opening bracket “(”
08:33 And here in this column type, cout and two opening angle brackets “<<”.
08:40 Now click on Replace All and click on Close.
08:45 We don't need the format specifier and '\n'
08:50 Let us delete them.
08:52 Now delete the comma and type two opening angle brackets.
09:01 Click on Save. Now delete the closing bracket.
09:04 Type two opening angle brackets again.
09:09 And within the double quotes type \n.
09:16 Now Click on Save.
09:20 Let us execute the program. Come back to our terminal.
09:24 To compile, type g++ space tokens dot cpp space hyphen o space tok1.
09:35 Here we have tok1 because we don't want to overwrite the output parameter tok for the file tokens.c.
09:46 Now press Enter.
09:48 To execute, type ./tok1 . Press Enter.
09:55 The output is displayed.
09:59 Now let us move on to some common errors which we can come across.
10:03 Come back to our program.
10:05 Suppose here I will reassign a new value to b as 8.
10:12 Now click on Save. Let us see what happens.
10:15 Come back to our terminal.
10:17 Let me clear the prompt.
10:22 Now compile as before.
10:26 We see an error at line no.7 in our tokens. cpp file.
10:32 "Assignment of read only variable 'b' ".
10:36 Come back to our program.
10:39 This is because 'b' is a constant. Constants are fixed values.
10:45 They do not change during the execution of program.
10:49 Hence it is giving an error. Let us fix the error.
10:54 Delete this. Click on Save.
10:57 Let us execute again. Come back to our terminal.
11:01 Compile as before.
11:03 Execute as before. Yes, it is working.
11:09 Now we will see another common error.
11:12 Switch back to our program.
11:15 Suppose here I will miss the single quotes. Click on Save.
11:21 Let us execute. Come back to our terminal.
11:25 Compile as before.
11:28 We see an error at line no.9 in our tokens dot cpp file.
11:34 " 'A' was not declared in the scope". Come back to our program.
11:40 This is because anything within the single quotes is considered as a character value.
11:47 And here we have declared 'd' as a character variable.
11:53 Let us fix the error. Type single quotes at line no.9 here.
11:59 Now Click on Save. Let us execute.
12:02 Come back to our terminal.
12:04 Now Compile as before.
12:06 Execute as before. Yes it is working.
12:13 Now switch back to our slides.
12:15 Let us summarize.In this tutorial we learnt,
12:18 Data types eg. int, double, float etc.
12:24 Variables eg. int a=2;
12:29 Identifiers eg. printf() and
12:34 Constant eg. double const b=4;
12:40 As an assignment,Write a program to calculate the simple interest.
12:45 Hint: principal * rate * time upon 100.
12:50 Watch the video available at the link shown below.
12:54 It summarizes the Spoken Tutorial project.
12:56 If you do not have good bandwidth, you can download and watch it.
13:01 The Spoken Tutorial Project Team:
13:03 Conducts workshops using spoken tutorials,
13:07 Gives certificates to those who pass an online test.
13:10 For more details, please write to contact @spoken-tutorial.org
13:19 Spoken Tutorial Project is a part of the Talk to a Teacher project.
13:24 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
13:30 More information on this Mission is available at the link shown below.
13:35 Ashwini Patil from IIT Bombay signing off .Thank You for joining.

Contributors and Content Editors

Jyotisolanki, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha

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