Study Code

Question 1

to_s

Answer 1

convert object to a string

Question 2

.reverse

Answer 2

reverses a string only

Question 3

.length

Answer 3

counts characters in a string only

Question 4

to_i

Answer 4

converts object to an integer

Question 5

to_a

Answer 5

converts object to an array [an array is a list in these types of brackets separated by commas]

Question 6

.max

Answer 6

a method to find the highest number in an array.

Question 7

What is being done here?

ticket = [12, 47, 35]

Answer 7

A variable is being created named “ticket”, which now defines the array of integers [12,47,35]. This new variable can now have methods called on it such as ticket.max to get the highest number in the array.

Question 8

.sort

Answer 8

sorts an array of integers from the lowest to the highest.

Question 9

.join

Answer 9

converts an array to a single string.

Question 10

What is the ! for in the below code

.sort!

Answer 10

The exclamation means the the array in which the sort method is being called on will permanently alter the array when completed.

Question 11

.clear

Answer 11

clears the called upon variable

example: > variable = “abcde”
variable. clear returns :> “”

Question 12

.downcase

Answer 12

converts a string to ALL lowercase “A” to “Z” characters only.

Question 13

.empty?

Answer 13

Asks if a string is empty or not.
Example:> “hello”.empty? returns false
““.empty? returns true

Question 14

What will the following code result in?

Variable.rstrip.lstrip

Answer 14

rstrip and lstrip will remove any white spaces from a string (right, or left sides). If no spaces are removed, will result in nil.

Question 15

What will the following code result in?

“ Now’s the time”.split

Answer 15

The .split method splits each word into a separate string using the empty white spaces to determine word beginning and end. Other types of characters can be used to split by defining at the end of the .split method.

Question 16

What will the following code result in?

books = { }

Answer 16

This action will create an empty hash named “books.” A hash can be considered a dictionary.

Question 17

If you have a hash named “Books,” what would the following code result in?
books.length

Answer 17

The code would return the amount of book titles in the hash.

Question 18

Describe the following code in detail.

books[“Jake’s Home Design Review”] = :quite_good.

Answer 18

This is a hash named “books”, which includes a book titled “Jake’s Home Design Review,” which is the KEY of the hash. Then there is a VALUE (noted by the :) which rates the book as quite good.

Question 19

If you had a hash named “books,” what would the following code result in?
books.keys

Answer 19

The book’s hash, if created with book titles as the keys, would return all the book titles in the hash.

Question 20

When a code word has : what is this called?

Answer 20

Symbol

Question 21

Blocks are always attached to what?

Answer 21

Block code is always attached to a method.
Example:> 5.times { print “Odelay!” }
This code will print Odelay! five times like
“Odelay!Odelay!Odelay!Odelay!Odelay!”

Question 22

Dir.entries “/” does what?

Answer 22

Lists all the top level directories in the program.

Question 23

In the following code, what is the code that follows the method?
Dir.entries “/”

Answer 23

The Dir is a variable; .entries is a method; and anything listed after a method is considered an attachment.

Question 24

What would the following code result in?

Dir[”/*.txt”]

Answer 24

This would look up only the .txt files in the directory.

Question 25

What would the following code result in?

print File.­read(“/com­ics.txt”)

Answer 25

It calls open the comics.txt file and prints to screen.

Question 26

What would the following code result in?

FileUtils.­cp(‘/comic­s.txt’, ‘/Hom­e/comics.t­xt’)

Answer 26

The FileUtils.cp would copy the comics.txt and paste it in the /Home directory (same file name in this case).

Question 27

What would the following code result in?

File.mtime(“/Home/comics.txt”)

Answer 27

It would give the time that the file comics.txt was created.

Example:> 2013-02-25 21:41:51 +0000

Question 28

When in the rails console, what would pressing the UP arrow accomplish?

Answer 28

The current cursor position would paste the last command entered from the previous cursor.

Question 29

What’s an argument?

Answer 29

Arguments are a list of things sent into a method, with commas separating them.
Example:> print “pre”, “event”, “something”, “another”

Question 30

Besides using { } to create a code block, what is another way of doing this?

Answer 30

By using DO and END. Can also be used in the command prompt which will create a .. cursor for the second line of code.

Question 31

What would the following code result in?
def load_comics(path)

Answer 31

This would create a method by defining (def) a method called load_comics followed by a list of arguments the method would need e.g. (path).

Question 32

These two lines of code are the same but used differently. Why?
entry.time = Time.now
@time = Time.now

Answer 32

When outside a class we use accessors like entry.time = Time.now; but inside a class we use instance variables like @time = Time.now.

Question 33

True or False?

Classes explain objects; how certain objects work.

Answer 33

True

Question 34

What is this character used for? (%)

Answer 34

It’s called a modulus and it is used with floating point numbers to gather the remainder of the the devision.

Question 35

Explain the following terms:
.to_f
.abs
.floor
.ceil
.to_i

Answer 35

.to_f = makes the number a floating number. So 4.to_f would then be 4.0.

.abs = gives the absolute value of the number. So a -3.abs would then be |3|

.floor = rounds down a floating number. So 4.2 would be 4.0

.ceil = rounds up a floating number. So 4.2 would be 5.0
.to_i = changes a number character to an integer.

Question 36

What is this called?

Example: puts “bob” + “ “ + “Smith”

Answer 36

It’s called string concatenation (string-wise addition).

Question 37

What is this character used for in Ruby? ()

Answer 37

It’s used as an escape. So “This is a newline \n it puts strings on a new line.” would have two lines of code. Two more examples:
“"These double quotes are escaped", he explained.”
or “Even the backslash ( \ ) is escaped.”

Question 38

What is this character called in programming? (!)

Answer 38

it’s called a BANG and it denotes a permanent revision to something.

Question 39

What is this character called in programming? (=)

Answer 39

It’s called an assignment operator.

Question 40

What does .chomp do?

Answer 40

It removes a newline (if it exists) from the end of a string. Example:
name = gets.chomp

Question 41

What value is always returned when using the “gets” method?

Answer 41

The value will ALWAYS be a string. Example: a number input would be just a character string. to change the value to an integer, use the .to_i

Question 42

What is this code used for? #{ }

Answer 42

It’s the string interpolation method which allows us to embed Ruby code or variable values without have to use the + operator to form the concatenation.

Question 43

What are two combined assignment operators in Ruby?

Answer 43

*= (this means we can now type this “num *= 4” instead of “num = num * 4”)

and

+= (this means we can now type this “num += 4” instead of “num = num + 4”)

Also, can use -=, /=, and %=.

Question 44

In Ruby, how must you name variables?

Answer 44

Variables must begin with a lowercase letter (a - z) or an underscore. After which they can be lower or upper.

Question 45

What is Syntactic Sugar?

Answer 45

When methods or code is abbreviated for ease of use like the operator methods +, *, /.

Question 46

What’s a method?

Answer 46

A method can be written in a Class or a Module; in a module it can be called without explicitly defining an instance object by just using the name and the arguments e.g. add(3,4).  A method begins with def and ends with end.  example
def method_name(parameter list)
guts of the method and a return
end