Difference between revisions of "C-and-C++/C3/Loops/English-timed"

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|Welcome to the spoken tutorial on Loops in C and C++  

|Welcome to the spoken tutorial on Loops in C and C++  

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|-

|In this tutorial we will learn,   

|In this tutorial we will learn,   

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|-

|'''for loop, '''  

|'''for loop, '''  

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|-

|'''while loop''' and  

|'''while loop''' and  

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|-

|'''do…while loop. '''

|'''do…while loop. '''

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|-

| We will do this with the help of some examples.  

| We will do this with the help of some 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  

|'''Ubuntu Operating System''' version 11.04  

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|-

| '''gcc''' and '''g++ Compiler''' version 4.6.1 on Ubuntu.  

| '''gcc''' and '''g++ Compiler''' version 4.6.1 on Ubuntu.  

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|-

|Let us start with the introduction to loops.  

|Let us start with the introduction to loops.  

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|-

|Loops are used to execute a group of instructions repeatedly.  

|Loops are used to execute a group of instructions repeatedly.  

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|-

|Depending on the purpose they are divided into three types:  

|Depending on the purpose they are divided into three types:  

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|-

|'''while loop '''  

|'''while loop '''  

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|-

|'''do…..while loop''' and

|'''do…..while loop''' and

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|-

|'''for loop '''

|'''for loop '''

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|-

|Let us start with the '''while loop''' first

|Let us start with the '''while loop''' first

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|A '''while loop''' tests the condition in the beginning  

|A '''while loop''' tests the condition in the beginning  

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|-

|The structure is  

|The structure is  

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|'''while''' ( condition )  

|'''while''' ( condition )  

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|within the bracket statement block  

|within the bracket statement block  

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|-

|Now move on to  '''do….while loop '''

|Now move on to  '''do….while loop '''

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|A '''do..while loop''' is executed atleast once before the condition could be validated.  

|A '''do..while loop''' is executed atleast once before the condition could be validated.  

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|The structure is

|The structure is

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|'''do''' (within the brackets) statement block  

|'''do''' (within the brackets) statement block  

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|after the bracket the '''while''' ( condition )

|after the bracket the '''while''' ( condition )

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|You can see that the condition is checked at the end.

|You can see that the condition is checked at the end.

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|-

|Now,let us see an example on '''while loop''' and '''do...while loop '''

|Now,let us see an example on '''while loop''' and '''do...while loop '''

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|-

|I have already typed the code on the editor.  

|I have already typed the code 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 '''while.c.'''

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

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|-

|Today we are going to learn addition of first 10 numbers using '''while''' loop.

|Today we are going to learn addition of first 10 numbers using '''while''' loop.

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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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|-

|Inside the '''main''' function we have declared two '''integer variables x''' and '''y '''and initialized to 0.

|Inside the '''main''' function we have declared two '''integer variables x''' and '''y '''and initialized to 0.

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| This is our '''while loop.'''  

| This is our '''while loop.'''  

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| The condition of the '''while''' loop is '''x is less than or equal to 10. '''

| The condition of the '''while''' loop is '''x is less than or equal to 10. '''

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|-

|Here the value of '''x''' is added to the value of '''y.'''

|Here the value of '''x''' is added to the value of '''y.'''

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| The value obtained after the addition is stored in '''y. '''

| The value obtained after the addition is stored in '''y. '''

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| Then we print the value of y

| Then we print the value of y

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| Here ''' x '''is incremented.  

| Here ''' x '''is incremented.  

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| That means the variable '''x''' is increased by one.

| That means the variable '''x''' is increased by one.

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|-

|And this is our '''return statement.'''

|And this is our '''return statement.'''

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|-

|Now,let us execute the program.  

|Now,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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|-

|Type '''gcc space while dot c space hyphen o space while '''

|Type '''gcc space while dot c space hyphen o space while '''

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|-

|Press '''Enter'''

|Press '''Enter'''

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|Type  '''./while ''' (dot slash while) .Press Enter

|Type  '''./while ''' (dot slash while) .Press Enter

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|-

| The output is displayed.

| The output is displayed.

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|-

| Now lets us see the working of ''' while loop.'''

| Now lets us see the working of ''' while loop.'''

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|-

|Let me resize the window.

|Let me resize the window.

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|Here, first the  value of  '''x ''' and  '''y ''' is 0

|Here, first the  value of  '''x ''' and  '''y ''' is 0

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|-

|This is our  '''while ''' condition.

|This is our  '''while ''' condition.

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|Here we check whether x is less than or equal to 10 which means the values of x will be from 0 to 10

|Here we check whether x is less than or equal to 10 which means the values of x will be from 0 to 10

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|Then we  add y plus x (i.e)  0 plus 0 we get 0.

|Then we  add y plus x (i.e)  0 plus 0 we get 0.

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| We print the value of y, here we get 0.  

| We print the value of y, here we get 0.  

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| Then x is incremented which means now the value of x will be 1

| Then x is incremented which means now the value of x will be 1

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|Then we  will check the condition again, 1 is less than or equal to 10, if the condition is  '''true ''' then we will add the values,

|Then we  will check the condition again, 1 is less than or equal to 10, if the condition is  '''true ''' then we will add the values,

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| y (i.e ) 0 plus x that is 1. 0 plus 1 is 1

| y (i.e ) 0 plus x that is 1. 0 plus 1 is 1

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|We print the value as 1.

|We print the value as 1.

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|-

|Again x is incremented.

|Again x is incremented.

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|Now the value of x is 2.

|Now the value of x is 2.

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|-

|We check the condition again.  

|We check the condition again.  

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|2 is less than or equal to 10, if the condition is  '''true ''' then we will add the values, (i.e ) 1 plus 2 which will give 3.

|2 is less than or equal to 10, if the condition is  '''true ''' then we will add the values, (i.e ) 1 plus 2 which will give 3.

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|We print the value as 3.  

|We print the value as 3.  

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|-

|Like this it will go on upto x is less than or equal to 10

|Like this it will go on upto x is less than or equal to 10

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|-

| Now, we will see the same program using  '''do….while loop  '''

| Now, we will see the same program using  '''do….while loop  '''

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|-

| Here is our program

| Here is our program

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|-

|Note that our file name is  '''do hyphen while dot c '''

|Note that our file name is  '''do hyphen while dot c '''

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|-

|This part is already explained in the previous program.  

|This part is already explained in the previous program.  

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|-

|So lets us move on to a  '''do...while loop '''

|So lets us move on to a  '''do...while loop '''

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|-

|Here first the body of the loop will be executed  and then the condition is checked.

|Here first the body of the loop will be executed  and then the condition is checked.

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|-

|The value of x is added to the value of y and the value obtained after the addition is stored in y

|The value of x is added to the value of y and the value obtained after the addition is stored in y

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|-

|The logic is same as in  '''while ''' program

|The logic is same as in  '''while ''' program

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|-

|Now lets us execute the program

|Now lets us execute the program

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|-

|Come back to our terminal

|Come back to our terminal

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|-

|Type  '''gcc space do hyphen while dot c space hyphen o space do '''. Press  '''Enter '''

|Type  '''gcc space do hyphen while dot c space hyphen o space do '''. Press  '''Enter '''

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|-

|Type  '''dot slash do '''. Press  '''Enter '''

|Type  '''dot slash do '''. Press  '''Enter '''

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|-

|We can see that the output is similar  to our  '''while ''' program

|We can see that the output is similar  to our  '''while ''' program

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|-

|Now, lets us see the working of  '''do...while loop '''

|Now, lets us see the working of  '''do...while loop '''

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|-

|Let me resize the window

|Let me resize the window

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|Here the value x and y is 0

|Here the value x and y is 0

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|-

|We add those values then we will get 0

|We add those values then we will get 0

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|-

|Now the value of y is 0.  

|Now the value of y is 0.  

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|-

|We print the value as 0

|We print the value as 0

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|-

|Then x is incremented by 1 which means now the value of x is 1, then the condition will be checked.

|Then x is incremented by 1 which means now the value of x is 1, then the condition will be checked.

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|-

| You can see that the body of loop is executed first.

| You can see that the body of loop is executed first.

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|-

|  Anyhow if the condition is  '''false ''' then also we will get a value that is 0.  

|  Anyhow if the condition is  '''false ''' then also we will get a value that is 0.  

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|-

|Now, here we will check whether 1 is less than or equal to 10

|Now, here we will check whether 1 is less than or equal to 10

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|-

|The condition is true again we will add the values.  

|The condition is true again we will add the values.  

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| Now 0 plus 1.  

| Now 0 plus 1.  

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| Then we will print the value of y as 1

| Then we will print the value of y as 1

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|Again x will be incremented.   

|Again x will be incremented.   

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|Now the value of x is 2.

|Now the value of x is 2.

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|-

|Then we check 2 is  less than or equal to 10

|Then we check 2 is  less than or equal to 10

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|-

|We will go back here

|We will go back here

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|Then we will add the values 1 plus 2 is 3

|Then we will add the values 1 plus 2 is 3

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| We print the value of y as 3

| We print the value of y as 3

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|Like this the conditions will be checked till the value of x will be less than or equal to 10

|Like this the conditions will be checked till the value of x will be less than or equal to 10

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|-

|And this is our return statement.

|And this is our return statement.

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|-

|Note that here the while condition ends with the semicolon

|Note that here the while condition ends with the semicolon

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|-

|In while loop the condition does not end with the semicolon.

|In while loop the condition does not end with the semicolon.

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|-

|Now lets us see how to execute these programs in C++

|Now lets us see how to execute these programs in C++

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|-

|This is our while program in C++

|This is our while program in C++

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|-

|The logic and implementation are same as in our C program

|The logic and implementation are same as in our C program

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|-

|There are a few changes like the header file as iostream in place of stdio.h

|There are a few changes like the header file as iostream in place of stdio.h

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|-

|We have included the using statement here using namespace std and here we have use the cout function in place of  '''printf ''' function

|We have included the using statement here using namespace std and here we have use the cout function in place of  '''printf ''' function

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|-

|The structure of  '''while loop ''' is same as in our C program.

|The structure of  '''while loop ''' is same as in our C program.

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|-

|Lets us execute the program

|Lets us execute the program

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|-

|Come back to a terminal

|Come back to a terminal

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|-

|Let me clear the prompt

|Let me clear the prompt

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|-

|To execute type  ''' g++ space while dot cpp space hyphen o space while1 '''. Press  '''Enter '''

|To execute type  ''' g++ space while dot cpp space hyphen o space while1 '''. Press  '''Enter '''

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|-

|Type  '''dot slash while1 '''.Press  '''Enter '''

|Type  '''dot slash while1 '''.Press  '''Enter '''

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|-

|You can see that the output is similar to our while program in C.

|You can see that the output is similar to our while program in C.

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|-

|Now let us see the  '''do... while ''' program in C++

|Now let us see the  '''do... while ''' program in C++

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|-

|Come back to the Text editor

|Come back to the Text editor

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|-

|Here also there are similar changes like the  '''header file ''',the  '''using statement ''' and the  '''cout  '''function

|Here also there are similar changes like the  '''header file ''',the  '''using statement ''' and the  '''cout  '''function

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|-

|Rest of the things are similar

|Rest of the things are similar

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|-

|Lets us execute the program.

|Lets us execute the program.

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|-

|Come back to our terminal

|Come back to our terminal

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|-

|Type  '''g++ space do hyphen while dot cpp space hyphen o space do1 '''. Press  '''Enter '''

|Type  '''g++ space do hyphen while dot cpp space hyphen o space do1 '''. Press  '''Enter '''

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|-

|Type  '''dot slash do1 '''.Press  '''Enter '''

|Type  '''dot slash do1 '''.Press  '''Enter '''

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|-

|We can see that the output is similar to our  '''do...while program in C. '''

|We can see that the output is similar to our  '''do...while program in C. '''

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|-

|Now we will see some common errors and their solutions

|Now we will see some common errors and their solutions

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|-

|Come back to our text editor

|Come back to our text editor

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|-

|Suppose here I will not increment the value of x.  

|Suppose here I will not increment the value of x.  

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|-

|Click on Save.  

|Click on Save.  

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|-

|Let us see what happens

|Let us see what happens

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|-

|Come back to the terminal.  

|Come back to the terminal.  

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|-

|Let me clear the prompt

|Let me clear the prompt

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|-

|Lets us execute the program.  

|Lets us execute the program.  

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|-

|Press the uparrow key twice.

|Press the uparrow key twice.

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|-

| Again press the uparrow key

| Again press the uparrow key

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|-

|The output is displayed.  

|The output is displayed.  

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|-

|We can see number of zeros, this is because the loop does not have the terminating condition .  

|We can see number of zeros, this is because the loop does not have the terminating condition .  

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|-

|It is known as  '''infinite loop. '''

|It is known as  '''infinite loop. '''

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|-

| '''Infinite loop ''' can cause the system to become unresponsive.

| '''Infinite loop ''' can cause the system to become unresponsive.

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|-

| It causes the program to consume all the  '''processors  time ''' but it can be terminated

| It causes the program to consume all the  '''processors  time ''' but it can be terminated

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|-

|Come back to our program, let us fix the error.  

|Come back to our program, let us fix the error.  

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|-

|Type  '''x++ ''' and a semicolon.

|Type  '''x++ ''' and a semicolon.

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|-

|Click on Save. Let us execute again.  

|Click on Save. Let us execute again.  

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|-

|Come back to terminal.

|Come back to terminal.

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|-

|Press the uparrow key

|Press the uparrow key

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|-

|Yes, it is working

|Yes, it is working

|-

|-

|This bring us to the end of this tutorial.  

|This bring us to the end of this tutorial.  

|-

|-

|We will move back to our slides.

|We will move back to our slides.

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|-

|Let us summarize

|Let us summarize

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|-

|In this tutorial we learned,  

|In this tutorial we learned,  

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|-

| '''while loop  '''

| '''while loop  '''

|-

|-

|example. while(x is less than or equal to 10)  

|example. while(x is less than or equal to 10)  

|-

|-

| '''do….while loop  '''

| '''do….while loop  '''

|-

|-

|example. do statement block and

|example. do statement block and

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|-

|while condition at the end

|while condition at the end

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|-

|As an assignment  

|As an assignment  

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|-

|Write a program to print the following using for loops  

|Write a program to print the following using for loops  

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|-

|0 to 9  

|0 to 9  

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|-

|The syntax of the  '''for loop ''' is  

|The syntax of the  '''for loop ''' is  

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|-

| '''for (variable initialization; variable condition;and variable increment or decrement)  '''

| '''for (variable initialization; variable condition;and variable increment or decrement)  '''

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|-

|And here will be the body of the loop

|And here will be the body of the loop

|-

|-

|Watch the video available at the link shown below

|Watch the video available at the link shown below

|-

|-

|It summarizes the Spoken Tutorial project  

|It summarizes 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 Talk to a Teacher project  

|Spoken Tutorial Project is a part of 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 script as been contributed by Dhawal Goyal. This is Ashwini Patil from IIT Bombay signing off  

|This script as been contributed by Dhawal Goyal. This is Ashwini Patil from IIT Bombay signing off  

|-

|-

|Thank You for joining.

|Thank You for joining.