Difference between revisions of "C-and-C++/C2/Scope-Of-Variables/English-timed"

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{| border=1
 
{| border=1
|| Time
+
|| '''Time'''
|| Narration
+
|| '''Narration'''
  
 
|-
 
|-
 
| 00:01
 
| 00:01
| Welcome to the spoken tutorial on Scope of variables in C and C++.
+
| Welcome to the spoken tutorial on '''Scope of variables in C and C++'''.
  
 
|-
 
|-
Line 17: Line 17:
 
|-
 
|-
 
| 00:13
 
| 00:13
| What is a Global variable?
+
|What is a Global variable?
  
 
|-
 
|-
Line 37: Line 37:
 
|-
 
|-
 
| 00:30
 
| 00:30
|'''Ubuntu Operating System''' version 11.04, '''gcc''' and '''g++''' '''Compiler''' version 4.6.1  
+
|'''Ubuntu Operating System''' version 11.04, '''gcc''' and '''g++ Compiler''' version 4.6.1.
  
 
|-
 
|-
 
|  00:41
 
|  00:41
|   Let us start with the introduction to the scope of variables.
+
| Let us start with the introduction to the scope of variables.
  
 
|-
 
|-
Line 49: Line 49:
 
|-
 
|-
 
| 00:54
 
| 00:54
|Depending on its type and place of declaration it is divided into two categories:
+
|Depending on it's type and place of declaration it is divided into two categories:
  
 
|-
 
|-
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|-
 
|-
 
|01:05
 
|01:05
| Now we will see an example,
+
| Now we will see an example.
  
 
|-
 
|-
 
| 01:07
 
| 01:07
|I have already typed the program on the editor,
+
|I have already typed the program on the editor.
  
 
|-
 
|-
 
| 01:10
 
| 01:10
|Let me open it
+
|Let me open it.
  
 
|-
 
|-
Line 85: Line 85:
 
|-
 
|-
 
|01:26
 
|01:26
| Here we have declared two global variables '''a and b.'''
+
|Here we have declared two global variables '''a and b.'''
  
 
|-
 
|-
Line 97: Line 97:
 
|-
 
|-
 
| 01:44
 
| 01:44
|These are declared outside any functions above main() funtion.
+
|These are declared outside any functions, above main() function.
  
 
|-
 
|-
 
| 01:51
 
| 01:51
|These have a Global scope.'''
+
|These have a '''global scope.'''
  
 
|-
 
|-
 
| 01:53
 
| 01:53
| Here we have declared a '''function''' '''add '''without''' arguments.'''
+
|Here we have declared a '''function''' '''add '''without''' arguments.'''
  
 
|-
 
|-
 
|01:59  
 
|01:59  
| Here sum is  a local variable it is declared inside the function add.
+
|Here 'sum' is  a local variable, it is declared inside the function '''add'''.
 
+
 
+
  
 
|-
 
|-
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|-
 
|-
 
| 02:19
 
| 02:19
|Then sum of a & b will be stored in the variable sum . Here we print the sum
+
|Then sum of a & b will be stored in the variable 'sum'. Here we print the sum.
  
 
|-
 
|-
 
| 02:29
 
| 02:29
| This is our '''main function.'''
+
| This is our '''main()''' function.
  
 
|-
 
|-
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|-
 
|-
 
| 02:38
 
| 02:38
| And This is our return statement.
+
| And this is our '''return''' statement.
  
 
|-
 
|-
 
|02:40
 
|02:40
| Now Click on save.
+
|Now click on Save.
  
 
|-
 
|-
 
| 02:43
 
| 02:43
| Let us execute the program.
+
|Let us execute the program.
  
 
|-
 
|-
 
| 02:45
 
| 02:45
| | 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.
  
 
|-
 
|-
 
| 02:55
 
| 02:55
| To compile type,
+
| To compile, type '''gcc space scope.c space hyphen o space sco''' and press Enter.
 
+
|-
+
| 02:56
+
|'''gcc space scope.c space hyphen o space sco''' and press enter.
+
  
 
|-
 
|-
 
| 03:05
 
| 03:05
|To execute
+
|To execute, type '''./sco''' (dot slash sco), press Enter.
 
+
|-
+
| 03:06
+
|Type'''./sco''' (dot slash), press enter
+
  
 
|-
 
|-
 
| 03:10
 
| 03:10
| the output is displayed as  
+
| The output is displayed as  
  
 
|-
 
|-
 
| 03:13
 
| 03:13
|'''Sum of a and b is 7'''
+
|'''Sum of a and b is 7'''.
  
 
|-
 
|-
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|-
 
|-
 
|  03:20
 
|  03:20
| Come back to our program. First press Shift ''Ctrl' & ''S'' key simultaneously on your keyboard
+
| Come back to our program. First press '''Shift, Ctrl''' & '''S''' keys simultaneously on your keyboard.
  
 
|-
 
|-
 
| 03:31
 
| 03:31
|Now Save the file''' '''with''' an extension .cpp ''' and click on save
+
|Now save the file with an extension '''.cpp ''' (dot cpp) and click on Save.
 
+
  
 
|-
 
|-
 
|  03:41
 
|  03:41
| Let us change the header file as'''iostream.'''
+
| Let us change the header file as '''iostream'''.
 
+
  
 
|-
 
|-
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|-
 
|-
 
| 03:58
 
| 03:58
| The  declaration of global variable and local variable is same in  C++
+
| The  declaration of global variable and local variable is same in  C++.
  
 
|-
 
|-
 
| 04:03
 
| 04:03
|So no need to change anything  
+
|So, no need to change anything.
  
 
|-
 
|-
 
|  04:07
 
|  04:07
| Now replace the '''printf '''statement with the '''cout''' statement
+
| Now replace the '''printf '''statement with the '''cout''' statement.
 
+
 
+
  
 
|-
 
|-
 
|  04:13
 
|  04:13
|   Delete the '''format specifier''' and '\n'  
+
| Delete the '''format specifier''' and '\n'.
  
 
|-
 
|-
 
| 04:17
 
| 04:17
|now delete the comma .
+
|Now delete the comma.
  
 
|-
 
|-
 
|  04:19
 
|  04:19
| Type two opening angle brackets
+
| Type two opening angle brackets.
  
 
|-
 
|-
 
| 04:22
 
| 04:22
|Delete the closing bracket, again type two opening angle bracket
+
|Delete the closing bracket, again type two opening angle brackets.
  
 
|-
 
|-
 
| 04:26
 
| 04:26
|and within the double quotes type backslash n. Now click on save
+
|And within the double quotes type backslash n. Now click on Save.
  
 
|-
 
|-
 
| 04:35
 
| 04:35
|Let us execute the program
+
|Let us execute the program.
 
+
  
 
|-
 
|-
 
| 04:39
 
| 04:39
|Come back to a terminal.
+
|Come back to our terminal.
  
 
|-
 
|-
 
| 04:42
 
| 04:42
| To compile type, '''g++ space scope dot cpp space -o space sco1, '''
+
| To compile, type '''g++ space scope dot cpp space -o space sco1 '''
 
+
  
 
|-
 
|-
 
| 04:52
 
| 04:52
| Here we have ,'''sco1'''because We don't want to overwrite output parameter sco for the file scope .c  
+
| Here we have '''sco1''' because we don't want to overwrite output parameter '''sco''' for the file 'scope.c'.
  
 
|-
 
|-
 
| 05:04
 
| 05:04
| now press enter
+
| Now press Enter.
 
+
  
 
|-
 
|-
 
| 05:07
 
| 05:07
| To execute type'''./sco1''' and press enter .  
+
| To execute type '''./sco1''' and press Enter.  
  
 
|-
 
|-
 
|05:14
 
|05:14
|The output is displayed as, '''Sum of a and b is 7.'''
+
|The output is displayed as  '''Sum of a and b is 7.'''
  
 
|-
 
|-
| 05:19
+
| 05:19
| We can see  that it is similar to our C code,
+
| We can see  that it is similar to our C code.
  
 
|-
 
|-
| 05:27
+
| 05:27
 
|Now we will see some common errors which we can come across.
 
|Now we will see some common errors which we can come across.
  
 
|-
 
|-
 
| 05:31
 
| 05:31
|Come back to our program, Suppose here I will declare a  variable '''a''' again,
+
|Come back to our program. Suppose here I will declare a  variable '''a''' again.
  
 
|-
 
|-
 
| 05:41
 
| 05:41
|Type '''int a ''' and a semicolon
+
|Type '''int a ''' and a semicolon.
  
 
|-
 
|-
| 05:45
+
| 05:45
| Click on save. We have declared  the variable ''a'' above the main function and after the add function ,
+
| Click on Save. We have declared  the variable 'a' above the main() function and after the '''add''' function.
  
 
|-
 
|-
| 05:55
+
| 05:55
 
| Let us see what happens.
 
| Let us see what happens.
 
  
 
|-
 
|-
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|-
 
|-
 
|06:01
 
|06:01
| Now compile as before ,
+
| Now compile as before.
 
+
  
 
|-
 
|-
 
|06:05
 
|06:05
|We see errors , Redefinition of ''int''a , ''int'' a previously defined here.   Come back to our program  
+
|We see errors, '''redefinition of 'int a' ''' , ''' 'int a' previously defined here'''. Come back to our program.
  
 
|-
 
|-
 
|06:18
 
|06:18
 
|'''a''' is a global variable.
 
|'''a''' is a global variable.
 
  
 
|-
 
|-
 
|06:20
 
|06:20
 
|It has a '''global scope.'''
 
|It has a '''global scope.'''
 
  
 
|-
 
|-
 
|06:22
 
|06:22
|We cannot declare the variable twice as it is already declared globally
+
|We cannot declare the variable twice as it is already declared globally.
 
+
  
 
|-
 
|-
 
|06:27
 
|06:27
 
|We can only declare '''variable a''' as a local variable .
 
|We can only declare '''variable a''' as a local variable .
 
 
  
 
|-
 
|-
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|-
 
|-
| 06:36
+
| 06:36
| Delete this .
+
| Delete this .
  
 
|-
 
|-
 
|  06:39
 
|  06:39
| Click on save.
+
| Click on Save.
  
 
|-
 
|-
 
|  06:41
 
|  06:41
| Let us execute again.
+
| Let us execute again Come back to our terminal.
 
+
 
+
|-
+
|06:42
+
|Come back to our terminal.
+
  
 
|-
 
|-
 
|  06:45
 
|  06:45
|  Now compile as before, execute as before.
+
|  Now compile as before, execute as before.
  
 
|-
 
|-
 
| 06:49
 
| 06:49
| Yes it is working.
+
| Yes, it is working.
 
+
  
 
|-
 
|-
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|-
 
|-
 
|  06:56
 
|  06:56
| let us summarise
+
| Let us summarize.
  
 
|-
 
|-
 
|  06:58
 
|  06:58
| In this tutorial we learn't ,
+
| In this tutorial we learnt ,
  
 
|-
 
|-
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|-
 
|-
 
|  07:07
 
|  07:07
| And local variable ,e.g:int sum
+
| and local variable ,e.g:int sum
  
 
|-
 
|-
 
|  07:12
 
|  07:12
|   As an assignment,
+
| As an assignment,
 
+
  
 
|-
 
|-
 
|07:14
 
|07:14
|Write a program to print the difference of two numbers.
+
|write a program to print the difference of two numbers.
  
 
|-
 
|-
 
| 07:19
 
| 07:19
 
| Watch the video available at the link shown below  .
 
| Watch the video available at the link shown below  .
 
  
 
|-
 
|-
 
|07:22
 
|07:22
|It summarises the Spoken Tutorial project.
+
|It summarizes the Spoken Tutorial project.
 
+
  
 
|-
 
|-
Line 402: Line 369:
 
|-
 
|-
 
| 07:30
 
| 07:30
| The Spoken Tutorial Project Team,
+
| The Spoken Tutorial Project Team:
 
+
  
 
|-
 
|-
 
|07:32
 
|07:32
|Conducts workshops using spoken tutorials .
+
|Conducts workshops using spoken tutorials,
 
+
  
 
|-
 
|-
 
|07:35
 
|07:35
 
|Gives certificates to those who pass an online test .
 
|Gives certificates to those who pass an online test .
 
  
 
|-
 
|-
Line 421: Line 385:
 
|-
 
|-
 
| 07:47
 
| 07:47
| 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.
 
+
  
 
|-
 
|-
 
|07:52
 
|07:52
 
|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.
 
  
 
|-
 
|-
 
|08:00
 
|08:00
 
|More information on this Mission is available at the link shown below
 
|More information on this Mission is available at the link shown below
 +
 
|-
 
|-
 
| 08:04  
 
| 08:04  
| This is Ashwini Patil from IIT Bombay signing off
+
| This is Ashwini Patil from IIT Bombay signing off.
 
+
  
 
|-
 
|-

Latest revision as of 12:57, 24 March 2017

Time Narration
00:01 Welcome to the spoken tutorial on Scope of variables in C and C++.
00:08 In this tutorial we will learn,
00:11 What is the Scope of variable?
00:13 What is a Global variable?
00:16 What is a Local variable?
00:19 Few examples.
00:22 We will also see some common errors and their solutions.
00:27 To record this tutorial, I am using
00:30 Ubuntu Operating System version 11.04, gcc and g++ Compiler version 4.6.1.
00:41 Let us start with the introduction to the scope of variables.
00:47 It is the region of code within which the variable can be accessed.
00:54 Depending on it's type and place of declaration it is divided into two categories:
00:59 Global Variable &
01:02 Local Variable.
01:05 Now we will see an example.
01:07 I have already typed the program on the editor.
01:10 Let me open it.
01:14 Note that our file name is scope.c.
01:19 Let me explain the code now.
01:23 This is our header file.
01:26 Here we have declared two global variables a and b.
01:32 And we have initialized them by assigning values as 5 and 2.
01:39 A global variable is available to all functions in your program.
01:44 These are declared outside any functions, above main() function.
01:51 These have a global scope.
01:53 Here we have declared a function add without arguments.
01:59 Here 'sum' is a local variable, it is declared inside the function add.
02:07 A local variable is available only to the function inside which it is declared.
02:13 These variables are declared inside a block.
02:16 These have local scope.
02:19 Then sum of a & b will be stored in the variable 'sum'. Here we print the sum.
02:29 This is our main() function.
02:33 The add function is called and then executed.
02:38 And this is our return statement.
02:40 Now click on Save.
02:43 Let us execute the program.
02:45 Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
02:55 To compile, type gcc space scope.c space hyphen o space sco and press Enter.
03:05 To execute, type ./sco (dot slash sco), press Enter.
03:10 The output is displayed as
03:13 Sum of a and b is 7.
03:16 Now let us see how to execute the same program in C++.
03:20 Come back to our program. First press Shift, Ctrl & S keys simultaneously on your keyboard.
03:31 Now save the file with an extension .cpp (dot cpp) and click on Save.
03:41 Let us change the header file as iostream.
03:47 Now include the using statement. Click on save .
03:58 The declaration of global variable and local variable is same in C++.
04:03 So, no need to change anything.
04:07 Now replace the printf statement with the cout statement.
04:13 Delete the format specifier and '\n'.
04:17 Now delete the comma.
04:19 Type two opening angle brackets.
04:22 Delete the closing bracket, again type two opening angle brackets.
04:26 And within the double quotes type backslash n. Now click on Save.
04:35 Let us execute the program.
04:39 Come back to our terminal.
04:42 To compile, type g++ space scope dot cpp space -o space sco1
04:52 Here we have sco1 because we don't want to overwrite output parameter sco for the file 'scope.c'.
05:04 Now press Enter.
05:07 To execute type ./sco1 and press Enter.
05:14 The output is displayed as Sum of a and b is 7.
05:19 We can see that it is similar to our C code.
05:27 Now we will see some common errors which we can come across.
05:31 Come back to our program. Suppose here I will declare a variable a again.
05:41 Type int a and a semicolon.
05:45 Click on Save. We have declared the variable 'a' above the main() function and after the add function.
05:55 Let us see what happens.
05:57 Come back to our terminal.
06:01 Now compile as before.
06:05 We see errors, redefinition of 'int a' , 'int a' previously defined here. Come back to our program.
06:18 a is a global variable.
06:20 It has a global scope.
06:22 We cannot declare the variable twice as it is already declared globally.
06:27 We can only declare variable a as a local variable .
06:34 Let us fix the error.
06:36 Delete this .
06:39 Click on Save.
06:41 Let us execute again Come back to our terminal.
06:45 Now compile as before, execute as before.
06:49 Yes, it is working.
06:52 This brings us to the end of this tutorial.
06:56 Let us summarize.
06:58 In this tutorial we learnt ,
07:00 Scope of variable,
07:02 Global variable, e.g : int a=5 &
07:07 and local variable ,e.g:int sum
07:12 As an assignment,
07:14 write a program to print the difference of two numbers.
07:19 Watch the video available at the link shown below .
07:22 It summarizes the Spoken Tutorial project.
07:25 If you do not have good bandwidth, you can download and watch it.
07:30 The Spoken Tutorial Project Team:
07:32 Conducts workshops using spoken tutorials,
07:35 Gives certificates to those who pass an online test .
07:40 For more details, please write to,contact@spoken-tutorial.org
07:47 Spoken Tutorial Project is a part of the Talk to a Teacher project.
07:52 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08:00 More information on this Mission is available at the link shown below
08:04 This is Ashwini Patil from IIT Bombay signing off.
08:08 Thank You for watching.

Contributors and Content Editors

Ashwini, Kavita salve, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14