C-and-C++/C2/Logical-Operators/English-timed
From Script | Spoken-Tutorial
| Time' | Narration |
| 00.02 | Welcome to the spoken tutorial on Logical operators in C and C++. |
| 00.08 | In this tutorial we will learn about:Logical operators like && Logical AND eg. expression1 && expression2 |
| 00.17 | Logical OR
eg. expression1 || expression2 |
| 00.21 | ! Logical NOT
eg. !(Expression1) |
| 00.25 | We will do this with the help of examples. |
| 00.28 | To record this tutorial, I am using:Ubuntu 11.10 as the operating system |
| 00.34 | gcc and g++ Compiler version 4.6.1 on Ubuntu. |
| 00.40 | Let us start with the introduction to the logical operators. |
| 00.44 | In C and C++, true is any value other than 0. |
| 00.49 | non zero means true |
| 00.51 | Non zero = True zero means falseZero = False
|
| 00.53 | Expressions using logical operators return 1 for true and 0 for false. |
| 00.59 | Now I'll explain the logical operators with the help of an example. |
| 01.04 | Here is the program for logical operators in C. |
| 01.09 | Inside the main block |
| 01.11 | This statement declares the variables a,b and c as integers. |
| 01.16 | The printf statement prompts the user to enter the values of a,b and c. |
| 01.22 | The scanf statement takes input from the user for the variables a, b and c. |
| 01.28 | Here, We are comparing the values of a with b and c to find the greatest. |
| 01.33 | To compare simultaneously, we use the logical AND operator. |
| 01.38 | Here, all of the conditions have to be true for logical AND to return a true value. |
| 01.44 | The expression is not evaluated further on encountering a false condition. |
| 01.49 | So, the expression (a>c) is evaluated only if (a>b) is true. |
| 01.57 | If a is less than b, then the expression won't be evaluated further. |
| 02.03 | This statement is evaluated if the previous condition is true. |
| 02.07 | Next (b>c) is evaluated. |
| 02.10 | If the condition is true, then b is greatest is displayed on the screen. |
| 02.17 | Otherwise c is greatest is displayed on the screen. |
| 02.21 | We now come to the logical OR operator. |
| 02.24 | Here, any one of the conditions has to be true for logical OR to return a true value. |
| 02.31 | The expression is not evaluated further on encountering a true condition. |
| 02.36 | So, if a == zero, then the remaining two expressions won't be evaluated. |
| 02.43 | This printf statement is executed if either of a, b or c is 0. |
| 02.49 | Coming to the end of the program. return 0 and ending curly bracket. |
| 02.54 | Now save the program. |
| 02.58 | Save it with extension .c |
| 03.00 | I have saved my file as logical.c |
| 03.04 | Open the terminal by pressing Ctrl, Alt and T keys simulataneously. |
| 03.09 | To compile the code type gcc logical.c -o log Press enter |
| 03.23 | To execute type ./log |
| 03.27 | Press Enter.
|
| 03.30 | I will enter the values as,
0 34 567 |
| 03.40 | The output is displayed as, |
| 03.43 | c is greatest. |
| 03.46 | The product of a, b and c is zero. |
| 03.50 | You should try executing this program with different sets of inputs. |
| 03.55 | Now Let's write the same program in C++ |
| 03.59 | I have already made the program and will take you through it. |
| 04.03 | Here is the code in C++. |
| 04.07 | Now to make the same program in C++, we make a few changes. |
| 04.12 | There's a change in the header file. |
| 04.15 | Using statement has been used. |
| 04.18 | Also there is a difference in output and input statements. |
| 04.22 | The operators behave in the same way as they did in C.
|
| 04.26 | Click on Save. |
| 04.27 | Make sure the file is saved with extension .cpp |
| 04.31 | Open the terminal by pressing Ctrl, Alt and T keys simulataneously. |
| 04.37 | To compile the program type g++ logical.cpp -o log1 |
| 04.49 | to execute type ./log1 |
| 04.54 | press Enter.
|
| 04.56 | I will enter the values as
0 34 567 |
| 05.02 | So We see the output is similar to the C program. |
| 05.05 | You should try executing the program with different sets of inputs too. |
| 05.10 | Now let us see an error which we can come across. |
| 05.13 | Let's switch to the editor. |
| 05.16 | Suppose here we forgot the brackets. |
| 05.20 | Delete this and this. |
| 05.26 | Let see what will happen, Save the program. |
| 05.31 | Come back to the terminal |
| 05.33 | Compile and execute as before |
| 05.38 | We see the error: |
| 05.41 | Expected identifier before '(' token. |
| 05.46 | This is because we have two different expressions here |
| 05.49 | We have to evaluate them as one expression using AND operator. |
| 05.53 | Now let us go back to our program and fix the error |
| 05.58 | Let us insert the brackets here and here. |
| 06.04 | Click on Save |
| 06.07 | Come back to the terminal. |
| 06.09 | Let us compile and execute as before |
| 06.14 | So it is working now. |
| 06.22 | Let us now summarize the tutorial. |
| 06.24 | In this tutorial we learnt about && Logical AND eg. ((a > b) && (a > c))
|
| 06.32 | Logical OR
eg. (a == 0 || b == 0 || c == 0)
|
| 06.40 | Assignment |
| 06.41 | Write a program that takes two numbers as input from the user. |
| 06.45 | Check whether the two numbers are equal or not using NOT operator. Hint: (a != b) |
| 06.54 | Watch the video available at the following link |
| 06.57 | It summarises the Spoken Tutorial project |
| 06.59 | If you do not have good bandwidth, you can download and watch it
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| 07.03 | The Spoken Tutorial Project Team * Conducts workshops using spoken tutorials |
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| 07.18 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 07.21 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
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| 07.30 | spoken hyphen tutorial dot org slash NMEICT hyphen Intro
|
| 07.37 | This is Ritwik Joshi from IIT Bombay.
Thank you for joining. |
