Difference between revisions of "C-and-C-Plus-Plus/C2/Increment-and-Decrement-Operators-in-C-and-C-Plus-Plus/English-timed"
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Latest revision as of 11:18, 9 April 2013
| Time' | Narration
|
| 00.02 | Welcome to the spoken tutorial on Increment and Decrement Operators in C and C++. |
| 00.09 | In this tutorial, we will learn about: |
| 00.11 | Increment and decrement operators
++ eg. a++ which is postfix increment operator. ++a which is prefix increment operator. - - eg. a- - is a postfix decrement operator. - -a is a prefix decrement operator.We will also learn about Type casting. |
| 00.36 | To record this tutorial, I am using: Ubuntu 11.10 as the operating system |
| 00.41 | gcc and g++ Compiler version 4.6.1 in Ubuntu. |
| 00.49 | The ++ operator increases the existing value of the operand by one. |
| 00.54 | a++ and ++a are equivalent to a = a + 1. |
| 01.01 | The -- operator decreases the existing value of the operand by one. |
| 01.07 | a-- and --a are equivalent to a = a - 1. |
| 01.14 | I will now demonstrate the use of increment and decrement operators with the help of a C program. |
| 01.20 | I have already made the program, so I'll explain the code. |
| 01.26 | Here, we have the code for increment and decrement operators in C. |
| 01.30 | Here, I have taken an integer variable a that holds the value 1. |
| 01.36 | This way we will be able to observe the changes in the value of a. |
| 01.40 | It will thus give us a better idea about the working of the operators. |
| 01.48 | Let's see how the postfix increment operator works. |
| 01.52 | The output of this printf statement is 1. |
| 01.56 | The value will change. |
| 01.58 | This is because the postfix operation occurs after the operand is evaluated. |
| 02.05 | If an operation is performed on a++, it is performed on the current value of a. |
| 02.11 | After that the value of a is incremented. |
| 02.18 | Now if we see the value of a here, it has been incremented by 1. |
| 02.28 | We again initialize a to 1 so as to reflect on the changes. |
| 02.36 | We now come to the prefix increment operators |
| 02.39 | This printf statement prints 2 on the screen. |
| 02.43 | This is because a prefix operation occurs before the operand is evaluated. |
| 02.50 | So the value of a is first incremented by 1 and then it is printed. |
| 02.59 | We again print a's value to see that there are no further changes. |
| 03.04 | Now lets check by executing this code. |
| 03.08 | I will comment out the following lines. Type /* ,*/ |
| 03.19 | Click on Save. |
| 03.23 | I have saved my file as incrdecr.c. |
| 03.30 | Open the terminal window by pressing Ctrl, Alt and T keys simultaneously. |
| 03.36 | To compile, type the following on the terminal gcc incrdecr.c -o incr. Press enter. |
| 03.52 | To execute the code, type ./incr'. Press enter. |
| 03.59 | The output is displayed on the screen, |
| 04.02 | This is the output when you print a++
|
| 04.06 | This is the output when you print ++a. |
| 04.10 | We can see that the result is as discussed before.
|
| 04.13 | Now Coming back to the rest of the code. |
| 04.17 | I will now explain the postfix and prefix decrement operators. |
| 04.22 | remove the multiline comment from here and here .
|
| 04.29 | We now again assign the value of 1 to a. |
| 04.36 | This printf statement outputs the value of 1 as explained previously. |
| 04.42 | A's value will be decremented after a-- is evaluated as its a postfix expression. |
| 04.51 | This printf statements output the value of 1 as explained previously
|
| 04.57 | A's value is now decremented by 1 after a-- is evaluated .As its a post fix expression |
| 05.03 | The next statement prints a's value as o. |
| 05.07 | A's value has now decremeted being1. |
| 05.10 | We now have the prefix decrement operator. |
| 05.14 | Output of this printf statement would be 0. |
| 05.17 | As it is a prefix operation. |
| 05.21 | The prefix operation occurs before the operand is evaluated. |
| 05.25 | This printf statements output is 0. |
| 05.28 | No further changes have being made to a's value. |
| 05.31 | Type return 0; And close the ending curly bracket |
| 05.37 | Click on Save. |
| 05.40 | Switch back to the terminal. |
| 05.43 | To compile type the following on the terminal; gcc incrdecr.c -o incr. Press Enter. |
| 05.58 | To execute type, ./incr.Press Enter.
|
| 06.08 | This is the output when you print a--
|
| 06.12 | This is the output when you print --a
|
| 06.15 | So, now we see how the increment and decrement operator works. |
| 06.21 | If we want to write the same program in C++. |
| 06.23 | I can make a few changes to the above C code. |
| 06.26 | Let me go back to the editor. |
| 06.29 | Here is the C++ file with the necessary code.
|
| 06.33 | Notice that the header is different from the C file header. |
| 06.37 | We have the using namespace statement here. |
| 06.40 | Also, note that the output statement in C++ is cout. |
| 06.45 | So, apart from these differences, the two codes are very similar. |
| 06.49 | Save the file. The file is saved with an extension .cpp |
| 06.56 | Let's compile the code. |
| 06.58 | Open the terminal and type g++ incrdecr.cpp -o incr. Press Enter. |
| 07.16 | To execute Type ./ incr.Press Enter. |
| 07.23 | The output is displayed on the screen:
|
| 07.27 | So, we see the output is identical to the C program. |
| 07.31 | We now have the concept of typecasting. |
| 07.33 | It is implemented the same way in both C and C++. |
| 07.38 | Typecasting is a used to make a variable of one type, act like another type. |
| 07.43 | Typecasting is done by enclosing the data type you want within parenthesis. |
| 07.49 | This cast is put in front of the variable you want to cast. |
| 07.54 | This typecast is valid for one single operation only. |
| 07.58 | Now a will behave as a float variable for a single operation. |
| 08.03 | Here is an example I have already created. |
| 08.06 | I shall now explain the code. |
| 08.11 | We first declare the variables a and b as integer and c as float. |
| 08.16 | a is assigned the value 5. b is assigned the value 2. |
| 08.22 | We will perform operations on a and b. |
| 08.26 | We divide a by b. The result of division is stored in c. |
| 08.30 | We have used %.2f to denote a precision of 2 decimal places. |
| 08.35 | The result displayed will be 2.00 against the expected result of 2.50. |
| 08.41 | The fractional part has been truncated as both the operands a and b are integers. |
| 08.47 | To perform real division one of the operands will have to be type cast to float. |
| 08.51 | Here we are typecasting a to float. c now holds the value of real division. |
| 08.57 | Now the result of real division is displayed. The answer is 2.50 as expected. |
| 09.03 | Type return 0; and close the ending curly bracket. |
| 09.07 | Click on Save. Save the file with .c extension. |
| 09.11 | I have saved my file as typecast.c. |
| 09.15 | Open the terminal. |
| 09.17 | To compile, type gcc typecast.c -o type.Press Enter. |
| 09.33 | to execute, type ./type.Press Enter. |
| 09.41 | The output is displayed on the screen.
|
| 09.44 | looking at the two values we see the effects of typecasting. |
| 09.48 | We will summarize the tutorial now. |
| 09.50 | In this tutorial we learnt, |
| 09.52 | How to use the increment and decrement operators. |
| 09.56 | We learn't about the form Postfix and Prefix
|
| 10.00 | Also we learnt about typecasting and how it is used. |
| 10.04 | As an assignment: |
| 10.05 | Write a program to solve the following expression, (a\b) + (c\d) |
| 10.12 | The values of a, b, c and d are taken as input from the user. |
| 10.17 | Use typecasting to perform real division. |
| 10.21 | Watch the video available at the following link |
| 10.24 | It summarises the Spoken Tutorial project |
| 10.27 | If you do not have good bandwidth, you can download and watch it
|
| 10.321 | The Spoken Tutorial Project Team |
| 10.34 | Conducts workshops using spoken tutorials |
| 10.36 | Gives certificates for those who pass an online test |
| 10.410 | For more details, please write to contact at spoken hyphen tutorial dot org
|
| 10.49 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 10.53 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 11.00 | More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro
|
| 11.11 | This is Ritwik Joshi from IIT Bombay.
Thank you for joining. |
