Lesson 1 | Basics

LITERALS
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'Hello world' // string
375 // integer
3.14 // float
true // boolan
{ 'a' => 1, 'b' =>2 } // hash
[ 1,2,3 ] // array
:sym // symbol
nil //nil


STRINGS 
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"The man said 'hi' ".
' The man said \'hi there \' '


irb :001 >a = 'ten'
=> "ten"

irb :002 => "my favorite number is #{a}"
=> "my favorite number is ten! "

String interpolation only works within double quotes


SYMBOLS
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:name
:a_symbol
:"suprisingly, this is a symbol"
NOTE: symbol is used when you want to reference something like a string but don't ever intend to print it to the screen or change it.


NUMBERS
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#integer and float 
# 1,2,3 | 1.1, 1.2, 1.3


NULL / Nill
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irb: 001> puts "hello world"
Hello, world
=> nill
NOTE: puts method prints out a string and returns nothing

irb: 002 > x = nill
=> nill

### check if something is nil or not ###
irb :001 > "hi" .nill?
=> false


An important property of the nil type is that when used in an expression, such as an if statement, it will be treated as false,
irb :001 > if nill
irb :002 > puts "hello world"
irb :003 > end
=> nil

NOTE: nil can be used within a conditional statement, and will be treated as false.
irb :001 > false == nil
=> false



OPERATIONS
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# Adding, Subtracting, Multiplying integers
irb :001 > 1 + 1
=> 2
irb :001 > 1 - 1
=> 0
irb :001 > 2 * 2
=> 4
irb :001 > 16 / 4
=> 4
irb :001 > 16 % 4
=> 0


irb :001 > 16.remainder(5) 
=> 1

irb :001 > 16.divmod(5)
=> \[3, 1\]



irb :001 > 4 ==4
=> true

irb :002 > 4 == 5
=> false

irb :001 > foo == 'foo'
=> true

irb :002 > 'foo' == 'bar'
=> false

irb :002 > '4' ==  4
=> false

// String concatenation
irb :001 > '1' + '1'
=> '11'

irb :002 > 'one' + 1
=> TypeError


TYPE CONVERSION
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irb :001 > '12'.to_i
=> 12

irb :002 > '4 hi there'.to_i
=> 4

irb :003 > 'hi there 4'.to_i
=> 0

irb :004 > '4'.to_f
=> 4.0

irb :005 > '4 hi there'.to_f
=> 4.0

irb :006 > 'hi there 4'.to_f
=> 0.0