week_1_diagnostic.md

Floats and Integers

What’s the difference between a float and integer?

An integer is a whole number, a float includes a decimal value

What’s are the similarities and differences between BigNum and FixNum?

A bignum is a number that exceeds the storage capacity of a fixnum. I'm not sure at ### what point that distinction occurs, and I'm not sure what different methods are available on both.

What will 4.0 / 2 return?

2.0

What will 1.5.to_i.to_f return?

1.0

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

The "*" is syntactic sugar (meaning shorthand) for a multiplication method. The "?" might also be sugar, but I'm not sure.

What will 10 % 3 return?

1

What will 5 == 10/2 return?

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

Strings

How can you grab the substring “ell” from “hello”? "hello"[1..3] Give an example of string concatenation and string interpolation. concatenation = "Hel" + "lo" interpolation = "Two plus two is #{2 + 2}" 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. bad style = javaScriptVar invalid = 1st_val good = times_bubbled

Arrays

How do you add to an array? shoveling, pushing, shifting

What will [1,2,3].shuffle do?

return an array with those three values in random order. Possibly [3,1,2]

What do shift and unshift do?

They insert and remove the first value from an array. Name 3 ways to retrieve 4 from this array: [4,3,5] [4,3,5][0] [4,3,5].first [4,3,5].unshift 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 |word| puts "The word is "#{word}"" end

Flow control

What’s the difference between a while and until loop?

A while loop operates if the condition evaluates to true, and the until loop iterates if the condition evaluates to false How do you escape a pry in the middle of a loop? exit

Enumerables (.each)

What is the purpose of an enumerable?

To operate on every value of a collection

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? new_array = [] array.each do |name| new_array << name[0] end

Classes and instance methods

When you’re defining a class, how do you store attributes? Many different ways, but I believe a conventional method would be defining them in the initialize method

What is the difference between attr_readers, attr_writers, and attr_accessors? ### What do each do?

Read/write access.

What method corresponds with .new when you create a new instance of a class?

I don't know. (Initialize)

Methods, arguments and scopes

Describe the scope that methods create. Are variables created in that scope accessible elsewhere?

What does the method scope have access to?

A new, local scope is created when a method is defined. Variables within that scope are not accessible outside. It does not have access to global variables unless they are fed into the method as an argument.