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.
|
| 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 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 ,
|
| 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=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 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
