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++'''.
  
 
|-
 
|-
−
| 00.08
+
| 00:08
 
|In this tutorial we will learn,
 
|In this tutorial we will learn,
  
 
|-
 
|-
−
| 00.11
+
| 00:11
 
| What is the Scope of variable?
 
| What is the Scope of variable?
  
 
|-
 
|-
−
| 00.13
+
| 00:13
−
| What is a Global variable?
+
|What is a Global variable?
  
 
|-
 
|-
−
| 00.16
+
| 00:16
 
| What is a Local variable?
 
| What is a Local variable?
  
 
|-
 
|-
−
| 00.19
+
| 00:19
 
|Few  examples.
 
|Few  examples.
  
 
|-
 
|-
−
| 00.22
+
| 00:22
 
|We will also see some common errors and their solutions.
 
|We will also see some common errors and their solutions.
  
 
|-
 
|-
−
|00.27
+
|00:27
 
| To record this tutorial, I am using
 
| To record this tutorial, I am using
  
 
|-
 
|-
−
| 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.
  
 
|-
 
|-
−
| 00.47
+
| 00:47
 
|It is the region of code within which the variable can be accessed.
 
|It is the region of code within which the variable can be accessed.
  
 
|-
 
|-
−
| 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:
  
 
|-
 
|-
−
| 00.59
+
| 00:59
 
|Global Variable &
 
|Global Variable &
  
 
|-
 
|-
−
| 01.02
+
| 01:02
 
|Local Variable.  
 
|Local Variable.  
  
 
|-
 
|-
−
|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.
  
 
|-
 
|-
−
| 01.14
+
| 01:14
 
|Note that our file name is '''scope.c.'''
 
|Note that our file name is '''scope.c.'''
  
 
|-
 
|-
−
| 01.19
+
| 01:19
 
|Let me explain the code now.
 
|Let me explain the code now.
  
 
|-
 
|-
−
| 01.23
+
| 01:23
 
|This is our '''header file.'''
 
|This is our '''header file.'''
  
 
|-
 
|-
−
|01.26
+
|01:26
−
| Here we have declared two global variables '''a and b.'''
+
|Here we have declared two global variables '''a and b.'''
  
 
|-
 
|-
−
| 01.32
+
| 01:32
 
|And we have '''initialized''' them by assigning values as '''5 and 2.'''
 
|And we have '''initialized''' them by assigning values as '''5 and 2.'''
  
 
|-
 
|-
−
| 01.39
+
| 01:39
 
|A global variable is available to all functions in your program.
 
|A global variable is available to all functions in your program.
  
 
|-
 
|-
−
| 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'''.
−
 
+
−
 
+
  
 
|-
 
|-
−
| 02.07
+
| 02:07
 
|A local variable is available only to the function inside which it is declared.
 
|A local variable is available only to the function inside which it is declared.
  
 
|-
 
|-
−
| 02.13
+
| 02:13
 
|These variables are declared inside a block.
 
|These variables are declared inside a block.
  
 
|-
 
|-
−
| 02.16
+
| 02:16
 
|These have '''local scope'''.
 
|These have '''local scope'''.
  
 
|-
 
|-
−
| 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.
  
 
|-
 
|-
−
| 02.33
+
| 02:33
 
| The '''add''' function is called and then executed.
 
| The '''add''' function is called and then executed.
  
 
|-
 
|-
−
| 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
+
| 03:05
−
|'''gcc scope.c -o sco''' and press enter.
+
|To execute, type '''./sco''' (dot slash sco), press Enter.  
  
 
|-
 
|-
−
| 03.05
+
| 03:10
−
|To execute
+
| The output is displayed as
  
 
|-
 
|-
−
| 03.06
+
| 03:13
−
|Type'''./sco''' press enter
+
|'''Sum of a and b is 7'''.
  
 
|-
 
|-
−
| 03.10
+
| 03:16
−
| the output is displayed as
+
| Now let us see how to execute the same program in C++.
  
 
|-
 
|-
−
| 03.13
+
| 03:20
−
|'''Sum of a and b is 7'''
+
| Come back to our program. First press '''Shift, Ctrl''' & '''S''' keys simultaneously on your keyboard.
  
 
|-
 
|-
−
| 03.16
+
| 03:31
−
| Now let us see how to execute the same program in C++.
+
|Now save the file with an extension '''.cpp ''' (dot cpp) and click on Save.  
  
 
|-
 
|-
−
|  03.20
+
|  03:41
−
| Come back to our program. First press Shift ''Ctrl' & ''S'' key simultaneously on your keyboard
+
| Let us change the header file as '''iostream'''.
  
 
|-
 
|-
−
| 03.31
+
| 03:47
−
|Now Save the file''' '''with''' an extension .cpp ''' and click on save  
+
| Now include the '''using '''statement. Click on save .
  
 +
|-
 +
| 03:58
 +
| The  declaration of global variable and local variable is same in  C++.
  
 
|-
 
|-
−
| 03.41
+
| 04:03
−
| Let us change the header file as'''iostream.'''
+
|So, no need to change anything.  
−
 
+
  
 
|-
 
|-
−
| 03.47
+
| 04:07
−
| Now include the '''using '''statement click on save .
+
| Now replace the '''printf '''statement with the '''cout''' statement.
  
 
|-
 
|-
−
| 03.58
+
| 04:13
−
| The  declaration of global variable  and local variable  is same in  C++
+
| Delete the '''format specifier''' and '\n'.
  
 
|-
 
|-
−
| 04.03
+
| 04:17
−
|So no need to change anything
+
|Now delete the comma.
  
 
|-
 
|-
−
|  04.07
+
|  04:19
−
| Now replace the '''printf '''statement with the  '''cout''' statement
+
| Type two opening angle brackets.
−
 
+
−
 
+
  
 
|-
 
|-
−
| 04.13
+
| 04:22
−
|   Delete the '''format specifier''' and '\n'
+
|Delete the closing bracket, again type two opening angle brackets.
  
 
|-
 
|-
−
| 04.17
+
| 04:26
−
|now delete the comma .
+
|And within the double quotes type backslash n. Now click on Save.
  
 
|-
 
|-
−
| 04.19
+
| 04:35
−
| Type two opening angle brackets
+
|Let us execute the program.
  
 
|-
 
|-
−
| 04.22
+
| 04:39
−
|Delete the closing bracket again type two opening  angle bracket
+
|Come back to our terminal.
  
 
|-
 
|-
−
| 04.26
+
| 04:42
−
|and within the double quotes type backslash n. Now click on save
+
| To compile, type '''g++ space scope dot cpp space -o space sco1 '''
  
 
|-
 
|-
−
| 04.35
+
| 04:52
−
|Let us execute the program
+
| Here we have '''sco1''' because we don't want to overwrite output parameter '''sco''' for the file 'scope.c'.
−
 
+
  
 
|-
 
|-
−
| 04.39
+
| 05:04
−
|Come back to a terminal.
+
| Now press Enter.  
  
 
|-
 
|-
−
| 04.42
+
| 05:07
−
| To compile type, '''g++ scope.cpp -o sco1, '''
+
| To execute type '''./sco1''' and press Enter.
−
 
+
  
 
|-
 
|-
−
| 04.52
+
|05:14
−
| Here we have ,'''./sco1''',  because We don't want to overwrite output parameter  sco for the file scope .c now press enter
+
|The output is displayed as  '''Sum of a and b is 7.'''
  
 
|-
 
|-
−
| 05.07
+
| 05:19
−
|  To execute type'''./sco1'''  and press enter . the output is displayed as,
+
| We can see that it is similar to our C code.  
  
 
|-
 
|-
−
|05.17
+
| 05:27
−
|'''Sum of a and b is 7.'''
+
|Now we will see some common errors which we can come across.
  
 
|-
 
|-
−
| 05.19
+
| 05:31
−
| we can see  that it is similar to our C code, Now we will see some common errors which we can come across.
+
|Come back to our program. Suppose here I will declare a  variable '''a''' again.
  
 
|-
 
|-
−
| 05.31
+
| 05:41
−
|Come back to our program, Suppose here I will declare a  variable '''a''' again,
+
|Type '''int a ''' and a semicolon.
  
 
|-
 
|-
−
| 05.41
+
| 05:45
−
|Type '''int a ;'''
+
| Click on Save. We have declared  the variable 'a' above the main() function and after the '''add''' function.
  
 
|-
 
|-
−
| 05.45
+
| 05:55
−
| Click on save. We have declared  the variable ''a'' above the main function and after the add function ,let us see what happens.
+
| Let us see what happens.
  
 
|-
 
|-
−
| 05.57
+
| 05:57
 
|Come back to our  terminal.
 
|Come back to our  terminal.
  
 
|-
 
|-
−
|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 .
−
 
−
 
  
 
|-
 
|-
−
|06.34
+
|06:34
 
|Let us fix the error.
 
|Let us fix the error.
  
 
|-
 
|-
−
| 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
+
| 06:45
−
|Come back to our terminal.
+
| Now compile as before, execute as before.
  
 
|-
 
|-
−
| 06.45
+
| 06:49
−
| Now  compile as before, execute as before.
+
| Yes, it is working.
  
 
|-
 
|-
−
| 06.49
+
|06:52
−
| Yes it is working.
+
|This brings us to the end of this tutorial.
−
 
+
  
 
|-
 
|-
−
|06.52
+
| 06:56
−
|This brings us to the end of this tutorial.
+
| Let us summarize.  
  
 
|-
 
|-
−
|  06.56
+
|  06:58
−
| let us summarise
+
| In this tutorial we learnt ,
  
 
|-
 
|-
−
|  06.58
+
|  07:00  
−
| In this tutorial we learn't ,
+
−
|-
+
−
|  07.00  
+
 
| Scope of variable,
 
| Scope of variable,
 +
 
|-
 
|-
−
|  07.02
+
|  07:02
 
| Global variable, e.g : int a=5 &
 
| Global variable, e.g : int a=5 &
 +
 
|-
 
|-
−
|  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.
−
 
+
  
 
|-
 
|-
−
|07.25
+
|07:25
 
|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.
  
 
|-
 
|-
−
| 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 .
−
 
  
 
|-
 
|-
−
|07.40
+
|07:40
 
|For more details, please write to,contact@spoken-tutorial.org
 
|For more details, please write to,contact@spoken-tutorial.org
  
 
|-
 
|-
−
| 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: http://spoken-tutorial.org\NMEICT-Intro.
+
|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.
−
 
+
  
 
|-
 
|-
−
|08.08
+
|08:08
 
|Thank You for watching.  
 
|Thank You for watching.  
  
 
|}
 
|}

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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