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{| border=1
 
{| border=1
−
|| ''Time'''
+
|| '''Time'''
 
|| '''Narration'''
 
|| '''Narration'''
  
 
|-
 
|-
−
|  00.01
+
|  00:01
−
| Welcome to the Spoken Tutorial on Arithmetic & Relational Operators in '''Ruby.'''
+
| Welcome to the '''Spoken Tutorial''' on '''Arithmetic & Relational Operators''' in '''Ruby.'''
  
 
|-
 
|-
−
| 00.06
+
| 00:06
−
| In this tutorial we will learn about  
+
| In this tutorial, we will learn about:
  
 
|-
 
|-
−
| 00.08
+
| 00:08
 
| Arithmetic Operators  
 
| Arithmetic Operators  
  
 
|-
 
|-
−
| 00.10
+
| 00:10
 
| Operator Precedence  
 
| Operator Precedence  
  
 
|-
 
|-
−
| 00.12
+
| 00:12
−
| Relational Operators
+
|Relational Operators.
  
 
|-
 
|-
−
|  00.14
+
|  00:14
−
|  Here we are using ''Ubuntu Linux '''version 12.04 '''Ruby''' 1.9.3
+
|  Here we are using:  '''Ubuntu Linux '''version '''12.04''' , '''Ruby 1.9.3'''
  
 
|-
 
|-
−
|  00.23
+
|  00:23
−
| To follow this tutorial you must know how to use Terminal and Text editor in Linux.
+
| To follow this tutorial, you must know how to use '''Terminal''' and '''Text editor''' in Linux.
  
 
|-
 
|-
−
|  00.28
+
|  00:28
−
|  You must also be familiar with '''irb '''
+
|  You must also be familiar with ''''irb'.'''
  
 
|-
 
|-
−
| 00.31
+
| 00:31
−
|If not, for relevant tutorials, please visit our website  
+
|If not, for relevant tutorials, please visit our website.
  
 
|-
 
|-
−
| 00.34
+
| 00:34
−
|Now let us learn about arithmetic operators.  
+
|Now, let us learn about arithmetic operators.  
  
 
|-
 
|-
−
|  00.38
+
|  00:38
−
| '''Ruby''' has following arithmetic operators.  
+
| '''Ruby''' has the following arithmetic operators.  
−
 
+
  
 
|-
 
|-
−
| 00.42
+
| 00:42
−
|'''+'''Addition: eg. a+b.  
+
|'+' Addition, e.g. a+b.  
  
 
|-
 
|-
−
|  00.45
+
|  00:45
−
|  - Subtraction: eg. a-b.  
+
|  '-' Subtraction, e.g. a-b.  
  
 
|-
 
|-
−
| 00.48
+
| 00:48
−
|'''/''' Division: eg. a/b.  
+
| '/' Division, e.g. a/b.  
  
 
|-
 
|-
−
| 00.51
+
| 00:51
−
|* Multiplication: eg. a*b.  
+
| '*' Multiplication, e.g. a*b.  
  
 
|-
 
|-
−
| 00.55
+
| 00:55
−
| % Modulus: eg. a%b.  
+
| '%' Modulus, e.g. a%b.  
  
 
|-
 
|-
−
| 00.59
+
| 00:59
−
|** Exponent : eg a**b  
+
| '**' Exponent,  e.g. a**b.
  
 
|-
 
|-
−
| 01.04
+
| 01:04
 
|Let us try these arithmetic operators using '''irb.'''  
 
|Let us try these arithmetic operators using '''irb.'''  
  
 
|-
 
|-
−
|  01.08
+
|  01:08
−
|  Open the terminal by pressing ''' Ctrl, Alt''' and ''' T '''keys simultaneously.  
+
|  Open the terminal by pressing ''' Ctrl, Alt''' and '''T '''keys simultaneously.  
  
 
|-
 
|-
−
| 01.14
+
| 01:14
−
|A terminal window appears on your screen.  
+
|A '''terminal window''' appears on your screen.  
  
 
|-
 
|-
−
| 01.17
+
| 01:17
−
| Type ''' irb''' and press Enter to launch the ''' interactive Ruby. '''
+
| Type "irb" and press '''Enter''' to launch the '''interactive Ruby. '''
  
 
|-
 
|-
−
| 01.21
+
| 01:21
−
|Type 10 plus 20 and press '''Enter. '''
+
|Type: 10 plus 20 and press '''Enter. '''
  
 
|-
 
|-
−
| 01.25
+
| 01:25
 
|The addition operation is performed and the result 30 is displayed.  
 
|The addition operation is performed and the result 30 is displayed.  
  
 
|-
 
|-
−
| 01.31
+
| 01:31
−
|Similarly the subtraction and multiplication operations can be performed.  
+
|Similarly, the subtraction and multiplication operations can be performed.  
  
 
|-
 
|-
−
|  01.35
+
|  01:35
 
|  Let us try the division operator.  
 
|  Let us try the division operator.  
  
 
|-
 
|-
−
|  01.38
+
|  01:38
−
|Type '''10 slash 4'''
+
|Type: '''10 slash 4'''
  
 
|-
 
|-
−
|  01.40
+
|  01:40
 
| and press '''Enter. '''
 
| and press '''Enter. '''
  
 
|-
 
|-
−
| 01.42
+
| 01:42
 
| Here you can see the result is truncated to the nearest whole number which is 2.
 
| Here you can see the result is truncated to the nearest whole number which is 2.
  
 
|-
 
|-
−
|  01.47
+
|  01:47
−
| To get a more accurate answer, we need to express one number as '''float'''
+
| To get a more accurate answer, we need to express one number as '''float'''.
  
 
|-
 
|-
−
| 01.52
+
| 01:52
−
|Type '''10.0 slash 4'''
+
|Type: '''10.0 slash 4'''
  
 
|-
 
|-
−
| 01.56
+
| 01:56
−
|and press '''Enter. '''
+
|and press '''Enter.'''
−
 
+
  
 
|-
 
|-
−
|  01.58
+
|  01:58
−
|  Now we get the result as 2.5
+
|  Now we get the result as 2.5.
  
 
|-
 
|-
−
| 02.01
+
| 02:01
 
| Let's now try the ''' modulus''' operator.  
 
| Let's now try the ''' modulus''' operator.  
  
 
|-
 
|-
−
| 02.05
+
| 02:05
 
|  The '''modulus''' operator returns the remainder as output.  
 
|  The '''modulus''' operator returns the remainder as output.  
−
 
  
 
|-
 
|-
−
| 02.09
+
| 02:09
−
|  Type '''12 percentage sign 5''' and press '''Enter'''
+
|  Type: '''12 percentage sign 5''' and press '''Enter'''.
  
 
|-
 
|-
−
|  02.15
+
|  02:15
−
|Here 12 is divided by 5 and the remainder 2 is returned back.  
+
|Here, 12 is divided by 5 and the remainder 2 is returned back.  
  
 
|-
 
|-
−
|  02.21
+
|  02:21
−
| Now let's try the '''exponent''' operator.  
+
| Now, let's try the '''exponent''' operator.  
  
 
|-
 
|-
 
|  02.24
 
|  02.24
−
| Type ''' 2 followed by the asterisk symbol twice and then 5''' and press '''Enter. '''
+
| Type: ''' 2''' followed by the asterisk symbol twice and then '''5''' and press '''Enter.'''
  
 
|-
 
|-
−
| 02.32
+
| 02:32
 
|This means that 2 is raised to the power of 5.
 
|This means that 2 is raised to the power of 5.
  
 
|-
 
|-
−
|  02.36
+
|  02:36
−
| So we get the output as 32.
+
| So, we get the output as 32.
  
 
|-
 
|-
−
| 02.39
+
| 02:39
 
|Next, let us learn about operator precedence.  
 
|Next, let us learn about operator precedence.  
  
 
|-
 
|-
−
|  02.44
+
|  02:44
 
| When several operations occur in a mathematical expression,  
 
| When several operations occur in a mathematical expression,  
  
 
|-
 
|-
−
| 02.47
+
| 02:47
 
| each part is evaluated  
 
| each part is evaluated  
  
 
|-
 
|-
−
| 02.50
+
| 02:50
 
|and resolved in a predetermined order called '''operator precedence'''.  
 
|and resolved in a predetermined order called '''operator precedence'''.  
  
 
|-
 
|-
−
| 02.56
+
| 02:56
−
|  This means that the operator which has ''' highest priority''' is executed first.  
+
|  This means that the operator which has the highest priority is executed first.  
  
 
|-
 
|-
−
| 03.01
+
| 03:01
−
|This is then followed by the next operator in the ''' priority''' order and so on.  
+
|This is then followed by the next operator in the priority order and so on.  
−
 
+
  
 
|-
 
|-
−
| 03.07
+
| 03:07
−
|This slide lists all operators from highest precedence to lowest.  
+
|This '''slide''' lists all operators from highest precedence to lowest.  
  
 
|-
 
|-
−
|  03.13
+
|  03:13
−
|  For example ''' 3 + 4 * 5 ''' returns 23 and not 35  
+
|  For example, ''' 3 + 4 * 5 ''' returns 23 and not 35.
  
 
|-
 
|-
−
| 03.23
+
| 03:23
−
|The multiplication operator (*) has higher precedence than the addition operator (+)  
+
|The multiplication operator asterisk (*) has higher precedence than the addition operator plus (+)  
  
 
|-
 
|-
−
| 03.29
+
| 03:29
 
|  and thus will be evaluated first.  
 
|  and thus will be evaluated first.  
−
 
  
 
|-
 
|-
−
| 03.32
+
| 03:32
−
|Hence four fives are twenty and then three is added to 20 to give the output as 23
+
|Hence, four fives are twenty and then three is added to 20 to give the output as 23.
  
 
|-
 
|-
−
| 03.42
+
| 03:42
−
|Lets us see some more examples based on operator precedence.  
+
|Let's see some more examples based on operator precedence.  
  
 
|-
 
|-
−
| 03.47
+
| 03:47
−
|  Let's go back to the terminal.
+
|  Let's go back to the terminal and
  
 
|-
 
|-
−
| 03.50
+
| 03:50
−
|Press ''' Crtl and L''' keys simultaneously to clear the irb console.  
+
|press ''' Crtl, L''' keys simultaneously to clear the '''irb''' console.  
  
 
|-
 
|-
−
|  03.56
+
|  03:56
−
|  Now type '''7 minus 2 multiply by 3 '''
+
|  Now, type: '''7 minus 2 multiply by 3 '''
  
 
|-
 
|-
−
|  04.03
+
|  04:03
−
|  and press '''Enter '''
+
|  and press '''Enter '''.
  
 
|-
 
|-
−
|  04.05
+
|  04:05
 
|  We get the answer as 1.
 
|  We get the answer as 1.
  
 
|-
 
|-
−
|  04.08
+
|  04:08
−
|  Here the ''' asterisk''' symbol has higher priority than the '''minus''' sign.  
+
|  Here, the asterisk symbol has higher priority than the minus sign.  
−
 
+
  
 
|-
 
|-
−
| 04.13
+
| 04:13
−
|So the multiplication opertion is performed first and then subtraction is performed.  
+
|So, the multiplication operation is performed first and then subtraction is performed.  
−
 
+
  
 
|-
 
|-
−
|  04.20
+
|  04:20
−
|   Lets us see an another example.  
+
| Let's see another example.  
  
 
|-
 
|-
−
|  04.22
+
|  04:22
−
|  Type Within brackets '''10 plus 2 slash 4 '''
+
|  Type: within brackets '''10 plus 2 slash 4 '''
  
 
|-
 
|-
−
| 04.29
+
| 04:29
−
|and Press '''Enter '''
+
|and press '''Enter'''. We get the answer as 3.
  
 
|-
 
|-
−
| 04.30
+
| 04:33
−
|  We get the answer as 3.
+
|In this case, () bracket has the higher priority than division (slash).
  
 
|-
 
|-
−
| 04.33
+
| 04:39
−
|In this case () bracket has the higher priority than division (slash)
+
|  So, the operation inside the bracket, that is addition, is performed first.
  
 
|-
 
|-
−
| 04.39
+
| 04:44
−
|  So the operation inside the bracket that is ''' addition''' is performed first.  
+
|  Then division is performed.  
  
 
|-
 
|-
−
| 04.44
+
|   04:47
−
|  Then ''' division''' is performed.  
+
|  Now, let us learn about '''Relational Operators'''.  
  
 
|-
 
|-
−
|   04.47
+
| 04:51
−
| Now, let us learn about Relational Operators.  
+
|Let's switch back to the slides.  
  
 
|-
 
|-
−
| 04.51
+
| 04:54
−
|Let's switch back to slides.  
+
| '''Relational operator'''s are also known as '''comparison''' operators.  
  
 
|-
 
|-
−
|  04.54
+
|  04:59
−
| Relational operators are also known as '''comparison''' operators.
+
−
 
+
−
|-
+
−
|  04.59
+
 
|  Expressions using relational operators return '''boolean''' values.  
 
|  Expressions using relational operators return '''boolean''' values.  
  
 
|-
 
|-
−
| 05.04
+
| 05:04
−
|Relation Operators in '''Ruby''' are  
+
|Relational operators in '''Ruby''' are-
  
 
|-
 
|-
−
| 05.07
+
| 05:07
−
|''' == Equals to'''  Eg. '''a==b '''
+
| ''' == Equals to''', e.g. a==b  
  
 
|-
 
|-
−
|  05.14
+
|  05:14
−
| ''' dot eql question mark'''  Eg. '''a.eql?b '''
+
| ''' dot eql question mark'''  e.g. a.eql?b  
  
 
|-
 
|-
−
| 05.21
+
| 05:21
−
|!= ''' Not equals to'''  Eg. ''' a exclamation equal b'''  
+
| '''!=  Not equals to'''  e.g.  '''a exclamation equals b'''  
  
 
|-
 
|-
−
|  05.28
+
|  05:28
−
| ''' Less than  Eg. a < b'''
+
| '''< Less than''' e.g. a < b  
  
 
|-
 
|-
−
|  05.32
+
|  05:32
−
|'''Greater than  Eg. a > b'''
+
| '''> Greater than''' e.g. a > b  
  
 
|-
 
|-
−
| 05.37
+
| 05:37
−
| ''' <= Lesser than or equal to  Eg.a less than arrow equal b'''  
+
| ''' <= Lesser than or equal to  e.g. a less than arrow equals b'''  
  
 
|-
 
|-
−
| 05.44
+
| 05:44
−
|''' >= Greater than or equal to  Eg.a greater than arrow equal b'''
+
| ''' >= Greater than or equal to''' e.g. a greater than arrow equals b  
  
 
|-
 
|-
−
| 05.49
+
| 05:49
−
|'''  <=> Combined comparison Eg.a less than arrow equal greater than equal b'''
+
| '''  <=> Combined comparison''' e.g. a less than arrow equal greater than arrow b.
  
 
|-
 
|-
−
| 05.56
+
| 05:56
−
| Now let us try some of these operators.  
+
| Now let us try some of these operators.  
  
 
|-
 
|-
−
| 06.00
+
| 06:00
 
|Go to the terminal.  
 
|Go to the terminal.  
  
 
|-
 
|-
−
| 06.02
+
| 06:02
−
| Press ''' ctrl, L''' keys simultaneously to clear the '''irb''' console.  
+
| Press '''ctrl, L''' keys simultaneously to clear the '''irb''' console.  
  
 
|-
 
|-
−
| 06.09
+
| 06:09
−
|  Lets us try ''' equals to''' operator.  
+
|  Let's try ''' equals to''' operator.  
  
 
|-
 
|-
−
| 06.11
+
| 06:11
−
|So type ''' 10 equals equals 10 '''
+
|So, type: ''' 10 equals equals 10 '''
−
 
+
−
 
+
  
 
|-
 
|-
−
| 06.16
+
| 06:16
−
|and Press ''' Enter'''  
+
|and press '''Enter'''. We get the output as "true".
  
 
|-
 
|-
−
| 06.17
+
| 06:20
−
|We get the output as ''' true.'''
+
|The '''.eql?''' opeartor is same as ''' equals to''' operator.
  
 
|-
 
|-
−
| 06.20
+
| 06:24
−
|''' .eql?''' opeartor is same as ''' equals to''' operator.  
+
|Let's try it out.  Now, type ''' 10 .eql?10''' and press '''Enter'''.
  
 
|-
 
|-
−
| 06.24
+
|06:33
−
|Lets try it out
+
|We get the output as "true".
  
 
|-
 
|-
−
| 06.25
+
| 06:35
−
| Now type ''' 10 .eql?10''' and Press Enter
+
|Now, let's try ''' not equal to''' operator.
  
 
|-
 
|-
−
|06.33
+
| 06:39
−
|We get the output as ''' true'''
+
| Type: ''' 10 not equal 10'''  
  
 
|-
 
|-
−
| 06.35
+
|06:44
−
|Now lets try ''' not equal to''' operator.  
+
| and press '''Enter'''.  
  
 
|-
 
|-
−
| 06.39
+
| 06:46
−
| Type ''' 10 not equal 10'''
+
|We get the output as "false".
  
 
|-
 
|-
−
|06.44
+
| 06:48
−
| And Press ''' Enter'''
+
−
 
+
−
|-
+
−
| 06.46
+
−
|We get the output as ''' false.'''
+
−
 
+
−
|-
+
−
| 06.48
+
 
|This is because the two numbers are equal.  
 
|This is because the two numbers are equal.  
−
 
  
 
|-
 
|-
−
| 06.51
+
| 06:51
 
|Clear the ''' irb''' console by pressing '''Ctrl, L''' simultaneously.  
 
|Clear the ''' irb''' console by pressing '''Ctrl, L''' simultaneously.  
  
 
|-
 
|-
−
|  06.56
+
|  06:56
−
|  Let us now try ''' less than''' operator.  
+
|  Now, let us try ''' less than''' operator.  
  
 
|-
 
|-
−
| 07.00
+
| 07:00
−
|Type ''' 10 less than 5''' and Press Enter
+
|Type: '''10 less than 5''' and press '''Enter'''.
−
 
+
  
 
|-
 
|-
−
|  07.05
+
|  07:05
−
|  Here if first operand is less than second then it will return ''' true'''
+
|  Here, if first operand is less than second then it will return "true".
  
 
|-
 
|-
−
| 07.10
+
| 07:10
−
|otherwise it will return ''' false'''  
+
|Otherwise, it will return "false".  
−
 
+
  
 
|-
 
|-
−
| 07.14
+
| 07:14
−
|We get the output as ''' false''' because 10 is not less than 5
+
|We get the output as "false" because 10 is not less than 5.
  
 
|-
 
|-
−
| 07.19
+
| 07:19
−
| We will now try '''greater than''' operator  
+
| We will now try '''greater than''' operator.
 
|-
 
|-
−
| 07.22
+
| 07:22
−
| Type '''5 greater than 2'''
+
| Type: '''5 greater than 2'''.
  
 
|-
 
|-
−
| 07.26
+
| 07:26
−
|Here if first operand is greater than second then it will return '''true '''
+
|Here, if first operand is greater than second then it will return "true";
  
 
|-
 
|-
−
| 07.31
+
| 07:31
−
|otherwise it will return '''false '''
+
|otherwise it will return "false".
  
 
|-
 
|-
−
| 07.34
+
| 07:34
−
|Press ''' Enter'''
+
|Press ''' Enter'''.
  
 
|-
 
|-
−
| 07.36
+
| 07:36
−
| In this case, we get the output as True because 5 is indeed greater than 2
+
| In this case, we get the output as "true" because 5 is indeed greater than 2.
  
 
|-
 
|-
−
| 07.42
+
| 07:42
−
|Clear the '''irb''' console by pressing ''' Ctrl, L''' simultaneously  
+
|Clear the '''irb''' console by pressing ''' Ctrl, L''' simultaneously.
  
 
|-
 
|-
−
| 07.47
+
| 07:47
−
| We will now try the '''less than equal to''' operator  
+
| We will now try the '''less than equal to''' operator.
  
 
|-
 
|-
−
|  07.51
+
|  07:51
−
|  Type '''12 less than equal 12 '''
+
|  Type: '''12 less than equal 12'''
−
 
+
  
 
|-
 
|-
−
| 07.56
+
| 07:56
−
|and Press '''Enter '''
+
|and press '''Enter'''.
−
 
+
 
   
 
   
 
|-
 
|-
−
| 07.59
+
| 07:59
−
| Here if first operand is less than or equal to second then it returns '''true'''
+
| Here, if first operand is less than or equal to the second then it returns "true";
  
 
|-
 
|-
−
| 08.04
+
| 08:04
−
| otherwise it returns '''false '''
+
| otherwise it returns "false".
  
 
|-
 
|-
−
| 08.07
+
| 08:07
−
|We get the output as '''True''' because 12 is equal to 12
+
|We get the output as "true" because 12 is equal to 12.
  
 
|-
 
|-
−
| 08.11
+
| 08:11
 
|You can try out the ''' greater than or equal to''' operator likewise.  
 
|You can try out the ''' greater than or equal to''' operator likewise.  
  
 
|-
 
|-
−
| 08.15
+
| 08:15
−
|Now let's try the '''combined comparision''' operator.  
+
|Now, let's try the '''combined comparison''' operator.  
  
 
|-
 
|-
−
| 08.19
+
| 08:19
−
|The ''' combined comparision''' operator  
+
|The ''' combined comparison''' operator:
  
 
|-
 
|-
−
| 08.21
+
| 08:21
−
|Returns '''0''' if first operand equals second  
+
| Returns 0 if first operand equals second  
−
 
+
  
 
|-
 
|-
−
| 08.24
+
| 08:24
−
|Returns 1 if first operand is greater than the second and  
+
| Returns 1 if first operand is greater than the second and  
−
 
+
−
 
+
  
 
|-
 
|-
−
| 08.29
+
| 08:29
−
|Returns -1 if first operand is less than the second operand  
+
|Returns -1 if first operand is less than the second operand.
−
 
+
  
 
|-
 
|-
−
| 08.34
+
| 08:34
−
|Let's see how it works with an example  
+
|Let's see how it works, with an example.
  
 
|-
 
|-
−
| 08.36
+
| 08:36
−
|Type '''3 less than equals greater than 3 '''
+
|Type: '''3 less than equals greater than 3 '''
  
 
|-
 
|-
−
| 08.41
+
| 08:41
−
|And Press '''Enter '''
+
|and press '''Enter'''.
−
 
+
  
 
|-
 
|-
−
| 08.43
+
| 08:43
 
|We get the output as 0
 
|We get the output as 0
  
 
|-
 
|-
−
| 08.45
+
| 08:45
−
|because both the operands are equal i.e. both are three  
+
|because both the operands are equal i.e. both are three.
  
 
|-
 
|-
−
| 08.50
+
| 08:50
−
|Now, let's change one of the operands to 4
+
|Now, let's change one of the operands to 4.
  
 
|-
 
|-
−
| 08.53
+
| 08:53
−
|Type '''4 less than equals greater than 3 '''
+
|Type: '''4 less than equals greater than 3 '''
−
 
+
 
   
 
   
 
|-
 
|-
−
| 08.58
+
| 08:58
−
|And Press '''Enter '''
+
|and press '''Enter'''.We get the output as 1
  
 
|-
 
|-
−
| 08.59
+
| 09:01
−
|We get the output as 1
+
|since 4 is greater than 3.
  
 
|-
 
|-
−
| 09.01
+
| 09:04
−
|Since 4 is greater than 3
+
|Now, let's change this example again.
−
 
+
  
 
|-
 
|-
−
| 09.04
+
| 09:07
−
|Now, let's change this example again
+
|Type: '''4 less than equals greater than 7 '''
  
 
|-
 
|-
−
| 09.07
+
| 09:11
−
|Type '''4 less than equals greater than 7 '''
+
|and press '''Enter '''.
−
 
+
  
 
|-
 
|-
−
| 09.11
+
| 09:13
−
|And Press '''Enter '''
+
|We get the output as -1. Since 4 is less than 7.
  
 
|-
 
|-
−
| 09.13
+
| 09:17
−
|We get the output as -1
+
|As an assignment,
  
 
|-
 
|-
−
| 09.14
+
| 09:19
−
|Since 4 is less than 7
+
|solve the following examples using '''irb''' and check the output:
−
 
+
  
 
|-
 
|-
−
| 09.17
+
| 09:24
−
|As an assignment
+
|''' 10 +  bracket 2 asterisk 5 bracket 8 slash 2'''
  
 
|-
 
|-
−
| 09.19
+
| 09:32
−
|Solve the following examples using irb and check the output
+
| '''4 asterisk 5 slash 2 plus 7'''
  
 
|-
 
|-
−
| 09.24
+
| 09:37
−
|''' 10 +  bracket 2 astreisk  5 bracket 8 slash 2'''
+
| Also, try arithmetic operators using '''method'''s.
  
 
|-
 
|-
−
| 09.32
+
| 09:42
−
|'''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.  
 
|This brings us to the end of this Spoken Tutorial.  
−
 
  
 
|-
 
|-
−
| 09.45
+
| 09:45
−
|Let's summarize  
+
|Let's summarize..
−
 
+
  
 
|-
 
|-
−
| 09.47
+
| 09:47
−
|In this tutorial we have learnt about  
+
|In this tutorial, we have learnt about:
  
 
|-
 
|-
−
| 09.49
+
| 09:49
−
|Arithmetic Operators  plus minus astreisk slash standing for addition, subtraction, multiplication, division.  
+
| Arithmetic Operators- plus, minus, asterisk, slash standing for addition, subtraction, multiplication, division.  
  
 
|-
 
|-
−
| 09.59
+
| 09:59
−
|Operator Precedence  
+
| Operator Precedence  
  
 
|-
 
|-
−
| 10.01
+
| 10:01
−
|Relational Operators  
+
| Relational Operators  
  
 
|-
 
|-
−
| 10.04
+
| 10:04
−
|using many examples  
+
| using many examples.
  
 
|-
 
|-
−
|  10.06
+
|  10:06
 
|  Watch the video available at the following link.
 
|  Watch the video available at the following link.
  
 
|-
 
|-
−
| 10.10
+
| 10:10
−
|It summarises the Spoken Tutorial project.
+
|It summarizes the Spoken Tutorial project.
  
 
|-
 
|-
−
| 10.14
+
| 10:14
 
|If you do not have good bandwidth, you can download and  watch it.  
 
|If you do not have good bandwidth, you can download and  watch it.  
  
 
|-
 
|-
−
|  10.18
+
|  10:18
−
| The Spoken Tutorial Project Team :
+
| The Spoken Tutorial project team:
  
 
|-   
 
|-   
−
| 10.20
+
| 10:20
−
|Conducts workshops using spoken tutorials  
+
| Conducts workshops using spoken tutorials.
  
 
|-
 
|-
−
|10.23
+
|10:23
−
|Gives certificates to those who pass an online test  
+
| Gives certificates to those who pass an online test.
  
 
|-
 
|-
−
| 10.26
+
| 10:26
−
|For more details, please write to contact@spoken-tutorial.org
+
|For more details, please write to: contact@spoken-tutorial.org
  
 
|-
 
|-
−
|  10.32
+
|  10:32
−
|  Spoken Tutorial Project is a part of the Talk to a Teacher project.
+
|  '''Spoken Tutorial''' project is a part of the '''Talk to a Teacher''' project.
  
 
|-
 
|-
−
| 10.36
+
| 10:36
 
|It is supported by the National Mission on Education through ICT, MHRD, Government of India.
 
|It is supported by the National Mission on Education through ICT, MHRD, Government of India.
  
 
|-
 
|-
−
| 10.43
+
| 10:43
−
|More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro
+
|More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
  
 
|-
 
|-
−
| 10.51
+
| 10:51
−
|This script has been contributed by the spoken tutorial team IIT Bombay  
+
|This script has been contributed by the spoken tutorial team, '''IIT Bombay'''.
  
 
|-
 
|-
−
| 10.57
+
| 10:57
−
|And this is Anjana Nair signing off  Thank you  
+
|And this is Anjana Nair, signing off. Thank you.
−
 
+
  
 
|}
 
|}

Latest revision as of 12:11, 10 March 2017


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 the following arithmetic operators.
00:42 '+' Addition, e.g. a+b.
00:45 '-' Subtraction, e.g. a-b.
00:48 '/' Division, e.g. a/b.
00:51 '*' Multiplication, e.g. a*b.
00:55 '%' Modulus, e.g. a%b.
00:59 '**' Exponent, e.g. 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 the 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 asterisk (*) has higher precedence than the addition operator plus (+)
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 Let's see some more examples based on operator precedence.
03:47 Let's go back to the terminal and
03:50 press Crtl, 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 operation is performed first and then subtraction is performed.
04:20 Let's see another example.
04:22 Type: within brackets 10 plus 2 slash 4
04:29 and press Enter. 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 the slides.
04:54 Relational operators are also known as comparison operators.
04:59 Expressions using relational operators return boolean values.
05:04 Relational operators in Ruby are-
05:07 == Equals to, e.g. a==b
05:14 dot eql question mark e.g. a.eql?b
05:21 != Not equals to e.g. a exclamation equals b
05:28 < Less than e.g. a < b
05:32 > Greater than e.g. a > b
05:37 <= Lesser than or equal to e.g. a less than arrow equals b
05:44 >= Greater than or equal to e.g. a greater than arrow equals b
05:49 <=> Combined comparison e.g. a less than arrow equal greater than arrow 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 Let's try equals to operator.
06:11 So, type: 10 equals equals 10
06:16 and press Enter. We get the output as "true".
06:20 The .eql? opeartor is same as equals to operator.
06:24 Let's try it out. Now, type 10 .eql?10 and press Enter.
06:33 We get the output as "true".
06:35 Now, let's 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 Now, let us 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 the 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 comparison operator.
08:19 The combined comparison 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.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. 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 asterisk 5 bracket 8 slash 2
09:32 4 asterisk 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, asterisk, 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 summarizes 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

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