Ruby/C2/Arithmetic-and-Relational-Operators/English-timed

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