Mod1 Week1 Diagnostic

Week 1 Diagnostic

Create a gist and answer the following questions.
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Floats and Integers

What’s the difference between a float and integer?
integer is a "whole" number whereas a float can contain a decimel point 

What’s are the similarities and differences between BigNum and FixNum?
no decimels, both are integers.  18 or 19 character number is a BigNum - below that is FixNum 

What will 4.0 / 2 return?
2.0

What will 1.5.to_i.to_f return?
1.5 to 1 to 1.0

What part of this expression ("hi" * 5?) is “syntactic sugar”? What does that mean?
n/a

What will 10 % 3 return?
1

What will 5 == 10/2 return?
true

How can you write 5 to the 2nd power?
5**2

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Strings

How can you grab the substring “ell” from “hello”?
"hello"[1..3]

Give an example of string concatenation and string interpolation.
"hi " + "you" ---- "this is a string of #{num} things"

Give examples of three variable names: a “valid name” (it will work) that goes against Ruby style, an “invalid” name (it will trigger an error), and a valid and stylistically conventional name.
will work but bad style = jasonloveschainsawsALOT
wont work 8isgreat
will work, good style = my_name_is

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Arrays

How do you add to an array?
<< push unshift 

What will [1,2,3].shuffle do?
shuffle the order of the items in the array 

What do shift and unshift do?
remove and insert the first item in an array 

Name 3 ways to retrieve 4 from this array: [4,3,5]
array[0]
array.shift
array.first

How would you print each word from this list (["hello", "goodbye", "cactus"]) to terminal within this output:
The word is "hello".

The word is "goodbye".

The word is "cactus".

array.each do |item|
 p "The word is '#{item}'"
 end


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Flow control

What’s the difference between a while and until loop?
while something is in this state do this thing, until this qualification is met do this this thing

How do you escape a pry in the middle of a loop?
exit 
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Enumerables (.each)

What is the purpose of an enumerable?
iterate over a group of items and perform functions on the individual items 

What are the two different ways that you can represent a block?
do end { }

Given this array ["Beth", "Lauren", "Ilana"]. How would you create a new array of just the first initials of each name?
initials = []
array.each do |item|
 initials << item[0]
 end


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Classes and instance methods

When you’re defining a class, how do you store attributes?
instance variables (?) 

What is the difference between attr_readers, attr_writers, and attr_accessors? What do each do?
just reads value, can't read it only write to it, can read and write to it

What method corresponds with .new when you create a new instance of a class?
in-IT-ialize 

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Methods, arguments and scopes

Describe the scope that methods create. Are variables created in that scope accessible elsewhere?
local, no

What does the method scope have access to?
global variables and sibling methods