Ruby Data Types

Integers & Floats

• Integers: numbers without decimals
  • 1
  • -1
  • 100_033_443
• Floats: numbers with decimals
  • 4.25
  • 8.275
  • -14.5

Integer & Float Methods

• Mathematical operations

4 + 3 #=> 7
7 * 2 #=> 14
45 % 10 #=> 5 (the modulo find the remainder)

• Comparison operators

4 == 4 #=> true
12 <= 8 #=> false
3 != 6 #=> true

Detour Variables

• Store Data

my_age = 30
your_age = 29
my_age == your_age
#=> false

Check

What will each line of code below return?

6 % 5
4 != 4
5 > 5
10 >= 10

Strings

• A series of characters between quotation marks
• Double quotes or single quotes so long as they match

String Methods

• #length
• #chars
• #upcase
• #downcase
• #capitalize

String Interpolation

name = "Sal"
"My name is #{name}"

Bracket Notation

"Sal"[1]

• Requires double quotes

Check

What will each line of code below return?

"Sal".upcase
"Megan"[3]
"Brian".chars

Changing Data Types

• .to_f - change an integer to a float
• .to_i - change a float to an integer
• .to_s - change an integer or float to a “string”

Arrays

["Sal", "Brian", "Megan"]
[1, 2, 3, 7, 2]
[1.5, 2.2, 3.3]
[[0, 0], [0, 1], [1, 0], [1, 1]]

• Ordered list that is comma-separated and enclosed in square brackets
• Count always starts at 0
• Can hold many pieces of data (we call each piece an element); or be empty!
• Can hold any data type - integer, string, hash, array

Array Methods

• array[0]
• length/count/size
• push/pop
• shift/unshift
• delete_at
• insert

Enumerables

• each
• map
• find
• select

Check

What will each line of code below return?

numbers = [5, 4, 7, 9]
numbers[0]
numbers.push(7)
numbers.pop
numbers.length
numbers.insert(1, 4)

Hashes

• Key value pair:

sal = {first_name: "Sal", last_name: "Espinosa", position: "Instructor", dogs: 0}
sal[:first_name]
#=> "Sal"
sal[:last_name]
#=> "Espinosa"

Check

What will each line of code below return?

spot = {age: 3, name: "Spot", breed: "Dalmation", siblings: ["Sadie", "Sarah", "Simone"]}
spot[:name]
spot[:age] = 4
spot[:siblings]
spot[:siblings].push("Sunny")
spot

Checks for Understanding

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