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

 

|Time

|Narration

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

|'''for loop, '''

 

|'''while loop''' and  

|'''do…while loop. '''

 

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

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

|'''while loop '''  

 

|'''do…..while loop''' and

|'''for loop '''

 

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

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

|The structure is  

 

| 01:01

|'''while''' ( condition )  

|within the bracket statement block  

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

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

|The structure is

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

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

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

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

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

| Then we print the value of y

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

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

|Press '''Enter'''

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

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

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

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

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

|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,

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

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

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

| Here is our program

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

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

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

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

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

|Now lets us execute the program

|Come back to our terminal

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

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

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

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

|Let me resize the window

|Here the value x and y is 0

|We add those values then we will get 0

|We print the value as 0

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

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

 

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

| Then we will print the value of y as 1

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

|We will go back here

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

| We print the value of y as 3

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

|And this is our return statement.

|Note that here the while condition ends with the semicolon

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

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

|This is our while program in C++

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

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

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

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

|Lets us execute the program

|Come back to a terminal

|Let me clear the prompt

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

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

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

|Come back to the Text editor

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

|Rest of the things are similar

|Come back to our terminal

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

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

|Now we will see some common errors and their solutions

|Come back to our text editor

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

|Click on Save.

 

|Let us see what happens

|Come back to the terminal.

 

|Let me clear the prompt

|Press the uparrow key twice.

| Again press the uparrow key

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

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

|Press the uparrow key

|Yes, it is working

|This bring us to the end of this tutorial.  

|Let us summarize

| '''while loop  '''

 

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

| '''do….while loop  '''

|while condition at the end

|As an assignment  

|Write a program to print the following using for loops  

|0 to 9  

| 10:12

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

|And here will be the body of the loop

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