Difference between revisions of "C-and-C++/C2/Scope-Of-Variables/English-timed"
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Revision as of 12:22, 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.
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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
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03.41 | Let us change the header file asiostream.
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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
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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
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04.39 | Come back to a terminal. |
04.42 | To compile type, g++ scope.cpp -o sco1,
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04.52 | Here we have ,./sco1, because We don't want to overwrite 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 ,
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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.
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06.20 | It has a global scope.
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06.22 | We cannot declare the variable twice as it is already declared globally
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06.27 | We can only declare variable a as a local variable .
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06.34 | Let us fix the error. |
06.36 | Delete this . |
06.39 | Click on save. |
06.41 | Let us execute again.
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06.42 | Come back to our terminal. |
06.45 | Now compile as before, execute as before. |
06.49 | Yes it is working.
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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=5 & |
07.07 | And local variable ,e.g:int sum |
07.12 | As an assignment,
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07.14 | Write a program to print the difference of two numbers. |
07.19 | Watch the video available at the link shown below .
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07.22 | It summarises the Spoken Tutorial project.
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07.25 | If you do not have good bandwidth, you can download and watch it. |
07.30 | The Spoken Tutorial Project Team,
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07.32 | Conducts workshops using spoken tutorials .
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07.35 | Gives certificates to those who pass an online test .
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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.
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07.52 | It is supported by the National Mission on Education through ICT, MHRD, Government of India.
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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
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08.08 | Thank You for watching. |
Contributors and Content Editors
Ashwini, Kavita salve, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14