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

|| Time

|| Narration

| Welcome to the spoken tutorial on Scope of variables in C and C++.

| What is a Global variable?

|'''Ubuntu Operating System''' version 11.04, '''gcc''' and '''g++''' '''Compiler''' version 4.6.1  

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

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

| Now we will see an example,

|I have already typed the program on the editor,

|Let me open it

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

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

|These have a Global scope.'''

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

| Here sum is  a local variable it is declared inside the function add.

 

 

|Then sum of a & b will be stored in the variable sum . Here we print the sum

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

| And This is our return statement.

| Now Click on save.

| Let us execute the program.

| | Please open the terminal window  by pressing '''Ctrl, ''Alt'' and T''' keys simultaneously on your keyboard.

| To compile type,

 

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

|To execute

 

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

| the output is displayed as  

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

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

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

 

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

 

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

|So no need to change anything  

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

 

 

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

|now delete the comma .

| Type two opening angle brackets

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

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

|Let us execute the program

 

|Come back to a terminal.

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

 

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

| now press enter

 

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

|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

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

|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

| Now compile as before ,

 

|We see errors , Redefinition of ''int''a , ''int'' a previously defined here.   Come back to our program  

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

 

| 06:36

| Delete this .

| Click on save.

| Let us execute again.

 

 

|Come back to our terminal.

|  Now compile as before, execute as before.

| Yes it is working.

 

| let us summarise

| In this tutorial we learn't ,

| And local variable ,e.g:int sum

|   As an assignment,

 

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

|It summarises the Spoken Tutorial project.

 

| The Spoken Tutorial Project Team,

 

|Conducts workshops using spoken tutorials .

 

| Spoken Tutorial Project is a part of the Talk to a Teacher project.

 

| This is Ashwini Patil from IIT Bombay signing off