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

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Revision as of 12:12, 12 August 2013

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 its 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() funtion.
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,
02.56 gcc scope.c -o sco and press enter.
03.05 To execute
03.06 Type./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 key simultaneously on your keyboard
03.31 Now Save the file with an extension .cpp and click on save


03.41 Let us change the header file asiostream.


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 bracket
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 a terminal.
04.42 To compile type, g++ scope.cpp -o sco1,


04.52 Here we have ,./sco1, because We don't want to overight output parameter sco1 file for the scope .c now press enter
05.07 To execute type./sco1 and press enter . the output is displayed as,
05.17 Sum of a and b is 7.
05.19 we can see that it is similar to our C code, 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 ;
05.45 Click on save. We have declared the variable a above the main function and after the add function ,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 inta , 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.


06.42 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 summarise
06.58 In this tutorial we learn't ,
07.00 Scope of variable,
07.02 Global variable, e.g : int a=s &
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 summarises 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: http://spoken-tutorial.org\NMEICT-Intro.
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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