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

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| 00:11
 
| 00:11
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|* What is the Scope of variable?
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| What is the Scope of variable?
  
 
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| 00:13
 
| 00:13
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|* What is a Global variable?
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|What is a Global variable?
  
 
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| 00:16
 
| 00:16
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|* What is a Local variable?
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| What is a Local variable?
  
 
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| 01:51
 
| 01:51
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|These have a '''Global scope.'''
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|These have a '''global scope.'''
  
 
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|01:59  
 
|01:59  
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|Here sum is  a local variable, it is declared inside the function add.
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|Here 'sum' is  a local variable, it is declared inside the function '''add'''.
  
 
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| 02:29
 
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| This is our '''main function.'''
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| This is our '''main()''' function.
  
 
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| 02:38
 
| 02:38
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| And this is our return statement.
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| And this is our '''return''' statement.
  
 
|-
 
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|02:40
 
|02:40
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| Now click on save.
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|Now click on Save.
  
 
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|-
 
| 02:43
 
| 02:43
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| Let us execute the program.
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|Let us execute the program.
  
 
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| 02:45
 
| 02:45
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| | Please open the terminal window  by pressing '''Ctrl, Alt''' and '''T''' keys simultaneously on your keyboard.
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|Please open the terminal window  by pressing '''Ctrl, Alt''' and '''T''' keys simultaneously on your keyboard.
  
 
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|-
 
| 02:55
 
| 02:55
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| To compile, type  
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| To compile, type '''gcc space scope.c space hyphen o space sco''' and press Enter.
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| 02:56
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|'''gcc space scope.c space hyphen o space sco''' and press enter.
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| 03:05
 
| 03:05
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|To execute,
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|To execute, type '''./sco''' (dot slash sco), press Enter.  
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| 03:06
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|type '''./sco''' (dot slash sco), press Enter.  
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| 03:10
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| The output is displayed as  
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| The output is displayed as  
  
 
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| 04:17
 
| 04:17
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|now delete the comma .
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|Now delete the comma.
  
 
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| 04:26
 
| 04:26
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|and within the double quotes type backslash n. Now click on Save.
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|And within the double quotes type backslash n. Now click on Save.
  
 
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| Here we have '''sco1''' because we don't want to overwrite output parameter '''sco''' for the file scope .c  
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| Here we have '''sco1''' because we don't want to overwrite output parameter '''sco''' for the file 'scope.c'.
  
 
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| 05:04
 
| 05:04
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| now press enter.  
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| Now press Enter.  
  
 
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| 05:07
 
| 05:07
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| To execute type '''./sco1''' and press enter.  
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| To execute type '''./sco1''' and press Enter.  
  
 
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| 05:19
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| 05:19
 
| We can see  that it is similar to our C code.  
 
| We can see  that it is similar to our C code.  
  
 
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|-
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| 05:27
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| 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.
  
 
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| 05:31
 
| 05:31
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|Come back to our program. Suppose here I will declare a  variable '''a''' again,
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|Come back to our program. Suppose here I will declare a  variable '''a''' again.
  
 
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| 05:45
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| 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.  
  
 
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|-
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| 05:55
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| 05:55
 
| Let us see what happens.
 
| Let us see what happens.
  
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|06:05
 
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|We see errors, Redefinition of ''int''a , ''int'' a previously defined here.   Come back to our program.  
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|We see errors, '''redefinition of 'int a' ''' , ''' 'int a' previously defined here'''. Come back to our program.  
  
 
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|06:22
 
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|We cannot declare the variable twice as it is already declared globally
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|We cannot declare the variable twice as it is already declared globally.
  
 
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| 06:36
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| 06:36
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| Delete this .
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| Delete this .
  
 
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|  06:39
 
|  06:39
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| Click on save.
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| Click on Save.
  
 
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|  06:41
 
|  06:41
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| Let us execute again.
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| Let us execute again Come back to our terminal.
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|06:42
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|Come back to our terminal.
+
  
 
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|  06:45
 
|  06:45
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|  Now compile as before, execute as before.
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|  Now compile as before, execute as before.
  
 
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| 06:49
 
| 06:49
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| Yes it is working.
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| Yes, it is working.
  
 
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|  06:56
 
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| let us summarise
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| Let us summarize.
  
 
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|  06:58
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| In this tutorial we learn't ,
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| In this tutorial we learnt ,
  
 
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|  07:07
 
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| And local variable ,e.g:int sum
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| and local variable ,e.g:int sum
  
 
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|  07:12
 
|  07:12
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|   As an assignment,
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| As an assignment,
  
 
|-
 
|-
 
|07:14
 
|07:14
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|Write a program to print the difference of two numbers.
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|write a program to print the difference of two numbers.
  
 
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| 07:30
 
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| The Spoken Tutorial Project Team,
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| The Spoken Tutorial Project Team:
  
 
|-
 
|-
 
|07:32
 
|07:32
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|Conducts workshops using spoken tutorials .
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|Conducts workshops using spoken tutorials,
  
 
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| 07:47
 
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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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|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

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