Difference between revisions of "Ruby/C2/Arithmetic-and-Relational-Operators/English-timed"
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Revision as of 17:03, 20 June 2014
| Time' | Narration |
| 00.01 | Welcome to the Spoken Tutorial on Arithmetic & Relational Operators in Ruby. |
| 00.06 | In this tutorial we will learn about |
| 00.08 | Arithmetic Operators |
| 00.10 | Operator Precedence |
| 00.12 | Relational Operators |
| 00.14 | Here we are using Ubuntu Linux version 12.04 Ruby' 1.9.3 |
| 00.23 | To follow this tutorial you must know how to use Terminal and Text editor in Linux. |
| 00.28 | You must also be familiar with irb |
| 00.31 | If not, for relevant tutorials, please visit our website |
| 00.34 | Now let us learn about arithmetic operators. |
| 00.38 | Ruby has following arithmetic operators.
|
| 00.42 | +Addition: eg. a+b. |
| 00.45 | - Subtraction: eg. a-b. |
| 00.48 | / Division: eg. a/b. |
| 00.51 | * Multiplication: eg. a*b. |
| 00.55 | % Modulus: eg. a%b. |
| 00.59 | ** Exponent : eg a**b |
| 01.04 | Let us try these arithmetic operators using irb. |
| 01.08 | Open the terminal by pressing Ctrl, Alt and T keys simultaneously. |
| 01.14 | A terminal window appears on your screen. |
| 01.17 | Type irb and press Enter to launch the interactive Ruby. |
| 01.21 | Type 10 plus 20 and press Enter. |
| 01.25 | The addition operation is performed and the result 30 is displayed. |
| 01.31 | Similarly the subtraction and multiplication operations can be performed. |
| 01.35 | Let us try the division operator. |
| 01.38 | Type 10 slash 4 |
| 01.40 | and press Enter. |
| 01.42 | Here you can see the result is truncated to the nearest whole number which is 2. |
| 01.47 | To get a more accurate answer, we need to express one number as float |
| 01.52 | Type 10.0 slash 4 |
| 01.56 | and press Enter.
|
| 01.58 | Now we get the result as 2.5 |
| 02.01 | Let's now try the modulus operator. |
| 02.05 | The modulus operator returns the remainder as output.
|
| 02.09 | Type 12 percentage sign 5 and press Enter |
| 02.15 | Here 12 is divided by 5 and the remainder 2 is returned back. |
| 02.21 | Now let's try the exponent operator. |
| 02.24 | Type 2 followed by the asterisk symbol twice and then 5 and press Enter. |
| 02.32 | This means that 2 is raised to the power of 5. |
| 02.36 | So we get the output as 32. |
| 02.39 | Next, let us learn about operator precedence. |
| 02.44 | When several operations occur in a mathematical expression, |
| 02.47 | each part is evaluated |
| 02.50 | and resolved in a predetermined order called operator precedence. |
| 02.56 | This means that the operator which has highest priority is executed first. |
| 03.01 | This is then followed by the next operator in the priority order and so on.
|
| 03.07 | This slide lists all operators from highest precedence to lowest. |
| 03.13 | For example 3 + 4 * 5 returns 23 and not 35 |
| 03.23 | The multiplication operator (*) has higher precedence than the addition operator (+) |
| 03.29 | and thus will be evaluated first.
|
| 03.32 | Hence four fives are twenty and then three is added to 20 to give the output as 23 |
| 03.42 | Lets us see some more examples based on operator precedence. |
| 03.47 | Let's go back to the terminal. |
| 03.50 | Press Crtl and L keys simultaneously to clear the irb console. |
| 03.56 | Now type 7 minus 2 multiply by 3 |
| 04.03 | and press Enter |
| 04.05 | We get the answer as 1. |
| 04.08 | Here the asterisk symbol has higher priority than the minus sign.
|
| 04.13 | So the multiplication opertion is performed first and then subtraction is performed.
|
| 04.20 | Lets us see an another example. |
| 04.22 | Type Within brackets 10 plus 2 slash 4 |
| 04.29 | and Press Enter |
| 04.30 | We get the answer as 3. |
| 04.33 | In this case () bracket has the higher priority than division (slash) |
| 04.39 | So the operation inside the bracket that is addition is performed first. |
| 04.44 | Then division is performed. |
| 04.47 | Now, let us learn about Relational Operators. |
| 04.51 | Let's switch back to slides. |
| 04.54 | Relational operators are also known as comparison operators. |
| 04.59 | Expressions using relational operators return boolean values. |
| 05.04 | Relation Operators in Ruby are |
| 05.07 | == Equals to Eg. a==b |
| 05.14 | dot eql question mark Eg. a.eql?b |
| 05.21 | != Not equals to Eg. a exclamation equal b |
| 05.28 | Less than Eg. a<b |
| 05.32 | Greater than Eg. a>b |
| 05.37 | <= Lesser than or equal to Eg.a less than arrow equal b |
| 05.44 | >= Greater than or equal to Eg.a greater than arrow equal b |
| 05.49 | <=> Combined comparison Eg.a less than arrow equal greater than equal b |
| 05.56 | Now let us try some of these operators. |
| 06.00 | Go to the terminal. |
| 06.02 | Press ctrl, L keys simultaneously to clear the irb console. |
| 06.09 | Lets us try equals to operator. |
| 06.11 | So type 10 equals equals 10
|
| 06.16 | and Press Enter |
| 06.17 | We get the output as true. |
| 06.20 | .eql? opeartor is same as equals to operator. |
| 06.24 | Lets try it out |
| 06.25 | Now type 10 .eql?10 and Press Enter |
| 06.33 | We get the output as true |
| 06.35 | Now lets try not equal to operator. |
| 06.39 | Type 10 not equal 10 |
| 06.44 | And Press Enter |
| 06.46 | We get the output as false. |
| 06.48 | This is because the two numbers are equal.
|
| 06.51 | Clear the irb console by pressing Ctrl, L simultaneously. |
| 06.56 | Let us now try less than operator. |
| 07.00 | Type 10 less than 5 and Press Enter
|
| 07.05 | Here if first operand is less than second then it will return true |
| 07.10 | otherwise it will return false
|
| 07.14 | We get the output as false because 10 is not less than 5 |
| 07.19 | We will now try greater than operator |
| 07.22 | Type 5 greater than 2 |
| 07.26 | Here if first operand is greater than second then it will return true |
| 07.31 | otherwise it will return false |
| 07.34 | Press Enter |
| 07.36 | In this case, we get the output as True because 5 is indeed greater than 2 |
| 07.42 | Clear the irb console by pressing Ctrl, L simultaneously |
| 07.47 | We will now try the less than equal to operator |
| 07.51 | Type 12 less than equal 12
|
| 07.56 | and Press Enter
|
| 07.59 | Here if first operand is less than or equal to second then it returns true |
| 08.04 | otherwise it returns false |
| 08.07 | We get the output as True because 12 is equal to 12 |
| 08.11 | You can try out the greater than or equal to operator likewise. |
| 08.15 | Now let's try the combined comparision operator. |
| 08.19 | The combined comparision operator |
| 08.21 | Returns 0 if first operand equals second
|
| 08.24 | Returns 1 if first operand is greater than the second and
|
| 08.29 | Returns -1 if first operand is less than the second operand
|
| 08.34 | Let's see how it works with an example |
| 08.36 | Type 3 less than equals greater than 3 |
| 08.41 | And Press Enter
|
| 08.43 | We get the output as 0 |
| 08.45 | because both the operands are equal i.e. both are three |
| 08.50 | Now, let's change one of the operands to 4 |
| 08.53 | Type 4 less than equals greater than 3
|
| 08.58 | And Press Enter |
| 08.59 | We get the output as 1 |
| 09.01 | Since 4 is greater than 3
|
| 09.04 | Now, let's change this example again |
| 09.07 | Type 4 less than equals greater than 7
|
| 09.11 | And Press Enter |
| 09.13 | We get the output as -1 |
| 09.14 | Since 4 is less than 7
|
| 09.17 | As an assignment |
| 09.19 | Solve the following examples using irb and check the output |
| 09.24 | 10 + bracket 2 astreisk 5 bracket 8 slash 2 |
| 09.32 | 4 astreisk 5 slash 2 plus 7 |
| 09.37 | Also, try arithmetic operators using methods |
| 09.42 | This brings us to the end of this Spoken Tutorial.
|
| 09.45 | Let's summarize
|
| 09.47 | In this tutorial we have learnt about |
| 09.49 | Arithmetic Operators plus minus astreisk slash standing for addition, subtraction, multiplication, division. |
| 09.59 | Operator Precedence |
| 10.01 | Relational Operators |
| 10.04 | using many examples |
| 10.06 | Watch the video available at the following link. |
| 10.10 | It summarises the Spoken Tutorial project. |
| 10.14 | If you do not have good bandwidth, you can download and watch it. |
| 10.18 | The Spoken Tutorial Project Team : |
| 10.20 | Conducts workshops using spoken tutorials |
| 10.23 | Gives certificates to those who pass an online test |
| 10.26 | For more details, please write to contact@spoken-tutorial.org |
| 10.32 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 10.36 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 10.43 | More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro |
| 10.51 | This script has been contributed by the spoken tutorial team IIT Bombay |
| 10.57 | And this is Anjana Nair signing off Thank you
|
Contributors and Content Editors
Devraj, PoojaMoolya, Pratik kamble, Sandhya.np14, Shruti arya
