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

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| 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++.

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|In this tutorial we will learn,

|In this tutorial we will learn,

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| What is the Scope of variable?

| What is the Scope of variable?

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| What is a Global variable?

| What is a Global variable?

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|-

| What is a Local variable?

| What is a Local variable?

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|Few  examples.

|Few  examples.

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|We will also see some common errors and their solutions.

|We will also see some common errors and their solutions.

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|-

| To record this tutorial, I am using

| To record this tutorial, I am using

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|-

|'''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  

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|  Let us start with the introduction to the scope of variables.

|  Let us start with the introduction to the scope of variables.

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|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.

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|Depending on its type and place of declaration it is divided into two categories:

|Depending on its type and place of declaration it is divided into two categories:

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|Global Variable &

|Global Variable &

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|Local Variable.  

|Local Variable.  

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| Now we will see an example,

| Now we will see an example,

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|I have already typed the program on the editor,

|I have already typed the program on the editor,

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|Let me open it

|Let me open it

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|Note that our file name is '''scope.c.'''

|Note that our file name is '''scope.c.'''

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|Let me explain the code now.

|Let me explain the code now.

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|This is our '''header file.'''

|This is our '''header file.'''

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| Here we have declared two global variables '''a and b.'''

| Here we have declared two global variables '''a and b.'''

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|And we have '''initialized''' them by assigning values as '''5 and 2.'''

|And we have '''initialized''' them by assigning values as '''5 and 2.'''

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|A global variable is available to all functions in your program.

|A global variable is available to all functions in your program.

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|These are declared outside any functions above main() funtion.

|These are declared outside any functions above main() funtion.

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|These have a Global scope.'''

|These have a Global scope.'''

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|  Here we have declared a '''function''' '''add '''without''' arguments.'''

|  Here we have declared a '''function''' '''add '''without''' arguments.'''

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|  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.

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|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.

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|These variables are declared inside a block.

|These variables are declared inside a block.

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|These have '''local scope'''.

|These have '''local scope'''.

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|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

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| This is our '''main function.'''

| This is our '''main function.'''

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| The '''add''' function is called and then executed.

| The '''add''' function is called and then executed.

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|  And This is our return statement.

|  And This is our return statement.

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| Now Click on save.

| Now Click on save.

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| Let us execute the program.

| Let us execute the program.

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| | 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.

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|  To compile type,

|  To compile type,

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|'''gcc space scope.c space hyphen o space sco''' and press enter.

|'''gcc space scope.c space hyphen o space sco''' and press enter.

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|To execute

|To execute

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|Type'''./sco''' (dot slash), press enter  

|Type'''./sco''' (dot slash), press enter  

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|  the output is displayed as  

|  the output is displayed as  

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|'''Sum of a and b is 7'''

|'''Sum of a and b is 7'''

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| Now let us see how to execute the same program in C++.

| Now let us see how to execute the same program in C++.

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|  Come back to our program. First press Shift ''Ctrl' & ''S'' key simultaneously on your keyboard

|  Come back to our program. First press Shift ''Ctrl' & ''S'' key simultaneously on your keyboard

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|Now Save the file''' '''with''' an extension .cpp ''' and click on save  

|Now Save the file''' '''with''' an extension .cpp ''' and click on save  

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| Let us change the header file as'''iostream.'''

| Let us change the header file as'''iostream.'''

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| Now  include the '''using '''statement. Click on save .

| Now  include the '''using '''statement. Click on save .

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| The  declaration of global variable  and local variable  is same in  C++

| The  declaration of global variable  and local variable  is same in  C++

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|So no need to change anything  

|So no need to change anything  

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|  Now replace the '''printf '''statement with the  '''cout''' statement

|  Now replace the '''printf '''statement with the  '''cout''' statement

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|  Delete the  '''format specifier''' and '\n'  

|  Delete the  '''format specifier''' and '\n'  

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|now delete the comma .

|now delete the comma .

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| Type two opening angle brackets

| Type two opening angle brackets

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|Delete the closing bracket, again type two opening  angle bracket  

|Delete the closing bracket, again type two opening  angle bracket  

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|and within the double quotes type backslash n. Now click on save

|and within the double quotes type backslash n. Now click on save

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|Let us execute the program

|Let us execute the program

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|Come back to a terminal.

|Come back to a terminal.

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| To compile type, '''g++ space scope dot cpp space -o space sco1, '''

| To compile type, '''g++ space scope dot cpp space -o space sco1, '''

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| Here we have ,'''sco1''',  because We don't want to overwrite output parameter  sco for the file scope .c  

| Here we have ,'''sco1''',  because We don't want to overwrite output parameter  sco for the file scope .c  

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| now press enter  

| now press enter  

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|  To execute type'''./sco1'''  and press enter .  

|  To execute type'''./sco1'''  and press enter .  

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|The output is displayed as,  '''Sum of a and b is 7.'''

|The output is displayed as,  '''Sum of a and b is 7.'''

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| 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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|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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|Come back to our program, Suppose here I will declare a  variable '''a''' again,

|Come back to our program, Suppose here I will declare a  variable '''a''' again,

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|Type '''int a ''' and a semicolon

|Type '''int a ''' and a semicolon

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|  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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| Let us see what happens.

| Let us see what happens.

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|Come back to our  terminal.

|Come back to our  terminal.

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| Now compile as before ,

| Now compile as before ,

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|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  

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|'''a''' is a global variable.

|'''a''' is a global variable.

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|It has a '''global scope.'''

|It has a '''global scope.'''

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|We cannot declare the variable twice as it is already declared globally

|We cannot declare the variable twice as it is already declared globally

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|We can only declare '''variable a''' as a local variable .

|We can only declare '''variable a''' as a local variable .

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|Let us fix the error.

|Let us fix the error.

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| Delete  this .

| Delete  this .

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| Click on save.

| Click on save.

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|  Let us execute again.  

|  Let us execute again.  

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|Come back to our terminal.

|Come back to our terminal.

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|  Now  compile as before, execute as before.

|  Now  compile as before, execute as before.

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|  Yes it is working.

|  Yes it is working.

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|This brings us to the end of this tutorial.

|This brings us to the end of this tutorial.

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| let us summarise  

| let us summarise  

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| In this tutorial we learn't ,

| In this tutorial we learn't ,

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| Scope of variable,

| Scope of variable,

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| Global variable, e.g : int a=5 &

| Global variable, e.g : int a=5 &

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| And  local variable ,e.g:int sum

| And  local variable ,e.g:int sum

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|  As an assignment,

|  As an assignment,

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|Write a program to print the difference of two numbers.

|Write a program to print the difference of two numbers.

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|-

| Watch the video available at the link shown below  .

| Watch the video available at the link shown below  .

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|-

|It summarises the Spoken Tutorial project.

|It summarises the Spoken Tutorial project.

|-

|-

|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.

|-

|-

| The Spoken Tutorial Project Team,  

| The Spoken Tutorial Project Team,  

|-

|-

|Conducts workshops using spoken tutorials .

|Conducts workshops using spoken tutorials .

|-

|-

|Gives certificates to those who pass an online test .

|Gives certificates to those who pass an online test .

|-

|-

|For more details, please write to,contact@spoken-tutorial.org

|For more details, please write to,contact@spoken-tutorial.org

|-

|-

|  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.

|-

|-

|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.

|-

|-

|More information on this Mission is available at the link shown below

|More information on this Mission is available at the link shown below

|-

|-

|  This is Ashwini Patil from IIT Bombay signing off

|  This is Ashwini Patil from IIT Bombay signing off

|-

|-

|Thank You for watching.  

|Thank You for watching.  

|}

|}