Nancyvarkey at 07:25, 23 March 2017

2017-03-23T07:25:30Z

Nancyvarkey: Created page with "{| border=1 || '''Time''' || '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Tokens''' in '''C and C Plus Plus'''. |- |00:06 | In this tutorial we will lea..."

2015-04-10T09:28:52Z

Created page with "{| border=1 || '''Time''' || '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Tokens''' in '''C and C Plus Plus'''. |- |00:06 | In this tutorial we will lea..."

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{| border=1
|| '''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,
|-
|00:21
| 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.

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|00:49
| I have already typed the code on the editor.

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|00:53
| Let me open it.

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|00:56
| Note that our file name is 'tokens.c'.

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|01:04
| In this program we will initialize the variables and print their values.

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|01:09
| Let me explain the code now.

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|01:12
| This is our header file.

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|01:16
| This is our main function.

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| 01:20
|Here,''' int '''is a '''keyword'''.

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|01:22
| The '''compiler''' knows the meaning of '''keyword'''.

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| 01:26
| '''a''' is an integer '''variable'''.

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| 01:28
| | We have assigned a value of '''2 '''to it.

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|01:32
| This is called as initialization.

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| 01:35
|If a value is not assigned to a variable then it is called as declaration of the variable.

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|01:43
| Here, '''b''' is a '''constant'''.

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| 01:46
| We have initialized 'b' by assigning a value of 4 to it.

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|01:53
| '''const''' keyword is used to create 'read only' variable.

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|01:58
| Let us switch back to our slides to know more about keywords and constant.

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| 02:06
| '''Keywords''' have fixed meanings that cannot be changed.

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|02:11
| '''Keywords''' cannot be used as '''variable''' names.

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|02:15
| There are 32''' keywords''' in C.

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|02:18
| To name some, '''auto''', '''break''', '''case''', '''char''', '''enum''', '''extern''', etc.

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| 02:28
|Constants: constants are fixed values.

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|02:33
| They do not change during the execution of a program.

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|02:38
| There are two types of constants, Numeric constants and Character constants.

|-
|02:45
| Now come back to our program.

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| 02:47
|Here, '''float''' is a data type of variable '''c'''.

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|02:52
| We have assigned it a value of '''1.5'''.

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|02:56
| '''Data type '''is a finite set of values along with a set of rules.

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| 03:04
| Here, '''d '''is a '''variable'''.

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|03:07
| '''char''' and single quotes suggest that we are dealing with a '''character'''.

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|03:12
| As a result, '''d''' is a '''character variable ''' storing the value '''A'''.

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| 03:20
| It is easy to see that '''int, double, float''' and '''char''' are data types.

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|03:30
| '''a,''' '''c''' and '''d''' are '''variables'''.

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|03:35
| Now come back to our slides.

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| 03:37
|We will know more about data types and variables.

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|03:48
|Data types: Let us begin with integer data type.

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|03:50
|It is declared as '''int'''.

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|03:53
| If we want to print an integer data type , we will use '''%d''' as the format specifier.

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| 04:01
| Similarly, we will use '''float''' and '''%f''' for floating point numbers.

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|04:09
|For character data type, we will use '''char''' and '''%c'''.

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|04:15
| And For double data type, we will use '''double''' and '''%lf''' as the format specifier.

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|04:24
| Now we will see the range of data types.

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|04:29
| '''Integer''' data type has a range of this

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|04:34
| '''Floating point''' has a range of this

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|04:39
| '''Character''' has a range of this

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|04:42
| And '''Double''' has a range of this

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| 04:47
|The values stored in the variable must not be greater or less than this range.

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|04:56
| Now we will move on to variables.

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|05:00
| Variable is a data name.

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|05:02
|It may be used to store a data value .

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|05:06
|The values can change when a program runs.

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|05:10
| Before using a variable it must be declared.

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|05:14
| We should try to give meaningful names to variables.

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|05:18
| example '''john''', '''marks''', '''sum''' etc.

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|05:24
| Now we will move back to our program.

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| 05:27
| Here,''' printf''' is the '''identifier''' name for this function.

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| 05:32
| |Come back to our slides.

|-
| 05:35
| Let us know about identifiers.

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| 05:38
| '''Identifiers''' are user defined names.

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|05:41
| An '''identifier '''consists of letters and digits.

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|05:46
| Both uppercase and lowercase letters are permitted.

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|05:51
| First character must be an alphabet or underscore.

|-
| 05:55
|Now Come back to our program.

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| 05:58
|Here we have initialized the variables and constants.

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| 06:02
|Here we print them.

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| 06:05
|And this is our return statement.

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| 06:08
|Now click on Save.

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| 06:10
| Let us execute the program.

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|06:12
| Please open the terminal window by pressing '''Ctrl,''' '''Alt''' and '''T''' keys simultaneously on your keyboard.

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|06:21
| To compile, type '''gcc space tokens dot c space hyphen o tok'''. Press Enter.

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| 06:30
| To execute, type '''./tok''' (dot slash tok).

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| 06:35
| The output is displayed.

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|06:39
| We can see that here we have six values after the decimal point.

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|06:44
| And here we have two values.

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| 06:48
| Now let us find out how this happened. Come back to our program.

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| 06:54
| This is because we have '''% point 2f''' here.

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|06:59
| It denotes that we can print only two values after the decimal point.

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| 07:04
| Suppose here I want an output with three decimal places.

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| 07:09
| Let us replace % point 2f with % point 3f.

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|07:16
| Now click on Save.

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|07:19
| Come back to our terminal.

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|07:22
| Compile as before, execute as before.

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| 07:28
|We see here three values after the decimal point.

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|07:33
|Now we will execute the same program in c++.

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|07:36
| Come back to our program.

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| 07:40
| I will change a few things here.

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| 07:42
| First press '''Shift+Ctrl+s''' keys simultaneously on your keyboard.

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| 07:50
| Now save the file with an extension '''.cpp''' and click on Save.

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| 07:58
|Let us change the header file as '''iostream'''

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| 08:03
| Now include the '''using '''statement.

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| 08:08
| And click on Save.

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| 08:11
|Now replace the '''printf '''statement with the '''cout''' statement

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|08:15
| since we use '''cout<<''' function to print a line in C++.

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| 08:21
| Click on Search for and replace text option.

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| 08:27
| Type here printf opening bracket “(”

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| 08:33
| And here in this column type, cout and two opening angle brackets “<<”.

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| 08:40
| Now click on Replace All and click on Close.

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| 08:45
| We don't need the '''format specifier''' and '\n'

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|08:50
| Let us delete them.

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|08:52
| Now delete the comma and type two opening angle brackets.

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| 09:01
|Click on Save. Now delete the closing bracket.

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|09:04
| Type two opening angle brackets again.

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|09:09
| And within the double quotes type \n.

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|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.

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|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.

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| 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.

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| 10:39
| This is because 'b' is a constant. Constants are fixed values.

|-
|10:45
|They do not change during the execution of program.

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| 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.

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|12:16
| In this tutorial we learnt,

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|12:18
|* Data types eg. int, double, float etc.

|-
|12:24
|* Variables eg. int a=2;

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|12:29
|* Identifiers eg. printf() and

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|12:34
|* Constant eg. double const b=4;

|-
| 12:40
| As an assignment,

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|12:41
| 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
| This is Jean Bonnet from IIT Bombay signing off .Thank You for joining.

|}

@@ Line 26: / Line 26: @@
 | To record this tutorial,
 |-
-|00:21
+|00:22
 | I am using '''Ubuntu Operating system version 11.10''',
@@ Line 623: / Line 623: @@
 |-
 |12:18
-|* Data types eg. int, double, float etc.
+|Data types eg. int, double, float etc.
 |-
 |12:24
-|* Variables eg. int a=2;
+|Variables eg. int a=2;
 |-
 |12:29
-|* Identifiers eg. printf() and
+|Identifiers eg. printf() and
 |-
 |12:34
-|* Constant eg. double const b=4;
+|Constant eg. double const b=4;
 |-

C-and-Cpp/C2/Tokens/English-USA - Revision history

Nancyvarkey at 07:25, 23 March 2017

Nancyvarkey: Created page with "{| border=1 || '''Time''' || '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Tokens''' in '''C and C Plus Plus'''. |- |00:06 | In this tutorial we will lea..."