C-and-C++/C3/Loops/English-timed
From Script | Spoken-Tutorial
| Time | Narration
| |
| 00.01 | Welcome to the spoken tutorial on Loops in C and C++ | |
| 00.06 | In this tutorial we will learn, | |
| 00.09 | for loop, | |
| 00.10 | while loop and | |
| 00.12 | do…while loop. | |
| 00.13 | We will do this with the help of some examples. | |
| 00.17 | We will also see some common errors and their solutions. | |
| 00.21 | To record this tutorial, I am using | |
| 00.24 | Ubuntu Operating System version 11.04 | |
| 00.28 | gcc and g++ Compiler version 4.6.1 on Ubuntu.
| |
| 00.34 | Let us start with the introduction to loops. | |
| 00.38 | Loops are used to execute a group of instructions repeatedly. | |
| 00.44 | Depending on the purpose they are divided into three types: | |
| 00.48 | while loop
| |
| 00.49 | do…..while loop and | |
| 00.51 | for loop | |
| 00.52 | Let us start with the while loop first | |
| 00.56 | A while loop tests the condition in the beginning | |
| 00.59 | The structure is | |
| 01.01 | while ( condition ) | |
| 01.03 | within the bracket statement block | |
| 01.07 | Now move on to do….while loop | |
| 01.09 | A do..while loop is executed at least once before the condition could be validated. | |
| 01.15 | The structure is | |
| 01.17 | do (within the brackets) statement block
| |
| 01.20 | after the bracket the while ( condition ) | |
| 01.23 | You can see that the condition is checked at the end. | |
| 01.27 | Now,let us see an example on while loop and do...while loop | |
| 01.32 | I have already typed the code on the editor. | |
| 01.35 | Let me open it. | |
| 01.37 | Note that our file name is while.c. | |
| 01.41 | Today we are going to learn addition of first 10 numbers using while loop. | |
| 01.47 | Let me explain the code now. | |
| 01.49 | This is our header file. | |
| 01.51 | Inside the main function we have declared two integer variables x and y and initialized to 0.
| |
| 01.59 | This is our while loop. | |
| 02.02 | The condition of the while loop is x is less than or equal to 10.
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| 02.06 | Here the value of x is added to the value of y.
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| 02.10 | The value obtained after the addition is stored in y. | |
| 02.15 | Then we print the value of y | |
| 02.18 | Here x is incremented. | |
| 02.20 | That means the variable x is increased by one. | |
| 02.25 | And this is our return statement. | |
| 02.27 | Now,let us execute the program. | |
| 02.30 | Please open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard. | |
| 02.39 | Type gcc space while dot c space hypen o space while | |
| 02.45 | Press Enter
| |
| 02.47 | Type ./ (dot slash) while .Press Enter
| |
| 02.52 | The output is displayed. | |
| 02.54 | Now lets us see the working of while loop. | |
| 02.57 | Let me resize the window. | |
| 03.00 | Here, first the value of x and y is 0
| |
| 03.04 | This is our while condition.Here we check whether x is less than or equal to 10 which means the values of x will be from 0 to 10 | |
| 03.15 | Then we add y plus x (i.e) 0 plus 0 we get 0. We print the value of y, here we get 0. Then x is incremented which means now the value of x will be 1 | |
| 03.33 | 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 | |
| 03.50 | We print the value as 1.Again x is incremented. | |
| 03.55 | Now the value of x is 2.We check the condition again. 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. | |
| 04.11 | We print the value as 3. Like this it will go on upto x is less than or equal to 10 | |
| 04.20 | Now, we will see the same program using do….while loop | |
| 04.24 | Here is our program | |
| 04.26 | Note that our file name is do hypen while.c | |
| 04.31 | This part is already explained in the previous program.So lets us move on to a do...while loop | |
| 04.38 | 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 | |
| 04.52 | The logic is same as in while program | |
| 04.55 | Now lets us execute the program | |
| 04.58 | Come back to our terminal | |
| 05.00 | Type gcc space do hypen while dot c space hypen o space do.Press Enter | |
| 05.08 | Type dot slash do. Press Enter | |
| 05.12 | We can see that the output is similiar to our while program | |
| 05.16 | Now, lets us see the working of do...while loop | |
| 05.20 | Let me resize the window | |
| 05.22 | Here the value x and y is 0 | |
| 05.25 | We add those values then we will get 0 | |
| 05.29 | Now the value of y is 0. We print the value as 0 | |
| 05.33 | Then x is incremented by 1 which means now the value of x is 1, then the condition will be checked. | |
| 05.40 | You can see that the body of loop is executed first. Anyhow if the condition is false then also we will get the values that is 0. | |
| 05.52 | Now, here we will check whether 1 is less than or equal to 10
| |
| 05.56 | The condition is true again we will add the values. Now 0 plus 1. Then we will print the value of y as 1 | |
| 06.05 | Again x will be incremented.Now the value of x is 2. Then we check 2 is less than or equal to 10 | |
| 06.15 | We will go back here | |
| 06.17 | Then we will add the values 1 plus 2 is 3 | |
| 06.20 | We print the value of y as 3 | |
| 06.23 | Like this the conditions will be checked till the value of x will be less than or equal to 10 | |
| 06.30 | And this is our return statement. | |
| 06.33 | Note that here the while condition ends with the semicolon | |
| 06.38 | In while loop the condition does not end with the semicolon. | |
| 06.43 | Now lets us see how to execute these programs in C++ | |
| 06.48 | This is our while program in C++ | |
| 06.52 | The logic and implementation are same as in our C program | |
| 06.56 | There are a few changes like the header file as iostream in place of stdio.h
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| 07.04 | We have included the using statement here using namespace std and here we have use the cout function in place of printf function | |
| 07.16 | The structure of while loop is same as in our C program. | |
| 07.21 | Lets us execute the program | |
| 07.23 | Come back to a terminal | |
| 07.25 | Let me clear the prompt
| |
| 07.28 | To execute type g++ space do , g++ space while dot cpp space hypen o space while1. Press Enter | |
| 07.41 | Type dot slash while1.Press Enter | |
| 07.46 | You can see that the output is similiar to our while program in C. | |
| 07.51 | Now let us see the do... while program in C++ | |
| 07.55 | Come back to the Text editor | |
| 07.57 | Here also there are similiar changes like the header file,the using statement and the cout function | |
| 08.06 | Rest of the things are similiar | |
| 08.09 | Lets us execute the program.Come back to our terminal | |
| 08.13 | Type g++ space do hypen while dot cpp space hypen o space do1. Press Enter | |
| 08.23 | Type dot slash do1.Press Enter | |
| 08.26 | We can see that the output is similiar to our do...while program in C. | |
| 08.32 | Now we will see some common errors and their solutions | |
| 08.35 | Come back to our text editor | |
| 08.38 | Suppose here I will not increment the value of x.Click on Save. Let us see what happens | |
| 08.46 | Come back to the terminal. Let me clear the prompt | |
| 08.50 | Lets us execute the program. Press the uparrow key twice. Again press the uparrow key | |
| 09.00 | The output is displayed. We can see number of zeros, this is because the loop does not have the terminating condition . It is known as infinite loop
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| 09.13 | Infinite loop can cause the system to become unresponsive. It causes the program to consume all the prossess time but it can be terminated | |
| 09.25 | Come back to our program let us fix the error. Type x++ and a semicolon. | |
| 09.31 | Click on Save. Lte us execute again. Come back to terminal. | |
| 09.36 | Press the uparrow key | |
| 09.41 | Yes, it is working | |
| 09.43 | This bring us to the end of the tutorial. We will move back to our slides. | |
| 09.49 | Let us summarize
| |
| 09.50 | In this tutorial we learned, | |
| 09.52 | while loop | |
| 09.53 | example. while(x is less than or equal to10) | |
| 09.57 | do….while loop | |
| 09.58 | example. do statement block and
| |
| 10.02 | while condition at the end | |
| 10.04 | As an assignment | |
| 10.06 | Write a program to print the following using for loops | |
| 10.10 | 0 to 9 | |
| 10.12 | The syntax of the for loop is | |
| 10.15 | for (variable initialization; variable condition;and variable increment or decrement) | |
| 10.24 | And here will be the body of the loop
| |
| 10.27 | Watch the video available at the link shown below | |
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| 11.05 | This script as been contributed by Dhawal Goyal. This is Ashwini Patil from IIT Bombay signing off | |
| 11.12 | Thank You for joining. |
