Ruby foundations quiz

ruby_foundations.rb

# PURPOSE ######################################################################

# This exercise aims not to practice or build skills, but to quickly identify
# topics and details of the Ruby language for further review. It intentionally
# ranges from easy to things that are probably hard or unknown.

# INSTRUCTIONS #################################################################

# There are 70 small tasks. Aim to spend one hour on them. If you don't know the
# answer just move on. If you are unsure of the syntax just guess. Answer
# inline, under each task description. The code doesn't have to execute. When a
# task extends a previous answer just copy and paste your old answer and
# continue. When the task doesn't specify certain details just make up whatever
# you want. Whenever the task asks you to print, you should probably use the
# puts method.


# TOPIC: NUMBERS ###############################################################

# Task 1: divide 3 by 2 to get 1.5

# Task 2: cast 1.000000001 into the integer 1

# Task 3: what is (1.999999999).to_int


# TOPIC: SYMBOLS ###############################################################

# Task 1: make symbols named chris, %age

# Task 2: make a symbol from the variable some_string


# TOPIC: STRINGS, ESCAPING AND INTERPOLATION ###################################

# Task 1: make a string

# Task 2: make a string with a " and a ' and a newline in it

# Task 3: with string interpolation make a string including variables myname and yourname

# Task 4: get the first letter of a string s


# TOPIC: VARIABLES #############################################################

# Task 1: assign a string to a variable


# TOPIC: NIL ###################################################################

# Task 1: What is the value of a variable you haven't set yet?

# Task 2: How can you tell if a variable is set to nil?


# TOPIC: ARRAYS ################################################################

# Task 1: assign an array of the numbers 1 to 3 to a variable, then append 4 to it

# Task 2: use the previous array to make a new one with 5 to 10 appended to it

# Task 3: get the first item from an array

# Task 4: get the last item from an array

# Task 5: get the 3rd to 5th items out of an array

# Task 6: get the second last and last items from an array

# Task 7: make an array that contains 3 arrays, each of 3 elements

# Task 8: from the string s = "one two three", generate an array ["one", "two", "three"]

# Task 9: from the array ["one", "two", "three"], generate a string "one;two;three"


# TOPIC: HASHES ################################################################

# Task 1: make a new empty hash

# Task 2: make hash mapping keys a, b, c to values 1, 2, 3

# Task 3: for hash h, set key d to value 4

# Task 4: retrieve from the hash the value associated with key b

# Task 5: get all the keys from a hash

# Task 6: get all the values from a hash

# Task 7: make a nested hash of scores broken down first by name, then by best/worst


# TOPIC: EXPRESSIONS AND OPERATOR PRECEDENCE ###################################

# Task 1: What is the result of `3 - 1 * 2`?

# Task 2: Make the above expression equivalent to `2 * 2` without removing anything


# TOPIC: CONDITIONALS: IF, UNLESS, BOOLEAN VALUES ##############################

# Task 1: use if/else to print 'small' if x is 1 or less, 'medium' if it is 2..5 and 'large' otherwise

# Task 2: use unless after the division num/denom to skip the division if denom is zero

# Task 3: set just_right to true if number n is 2..5, false otherwise, without using if/else

# Task 4: set not_right to to the opposite of of just_right

# Task 5: rewrite not_right without using just_right, or !/not, or if/else


# TOPIC: REGULAR EXPRESSIONS ###################################################

# Task 1: print 'yes' if a string s begins with 'start', using regular expressions

# Task 2: extract the *bold* word from "hello world what's *up*?" using a regular expression


# TOPIC: CONSTANTS #############################################################

# Task 1: define a constant to represent a maximum number of retries, set it to 15


# TOPIC: CLASS DEFINITION, INSTANTIATION #######################################

# Task 1: define a class Animal

# Task 2: instantiate an Animal object


# TOPIC: METHOD DEFINITION, INVOCATION, DEFAULT, KEYWORD & HASH ARGS, SPLAT ####

# Task 1: on Animal, define an instance method hi, which takes a name prints hello <name>

# Task 2: invoke the method Animal#hi

# Task 3: set a default value 'you' for the name argument

# Task 4: make the name argument a keyword argument

# Task 5: define a class method Animal.pair that returns an array of two animal objects

# Task 6: define a new global method h that takes an options hash and prints it out

# Task 7: invoke h with options start of 3 and size of 5

# Task 8: use the splat operator to pass the contents of an array args to a method a


# TOPIC: PRIVATE METHODS #######################################################

# Task 1: define a private method Animal#pretty_print which just prints a string


# TOPIC: LOCAL AND INSTANCE VARIABLES, SCOPE ###################################

# Task 1: in Animal#hi, assign the message string to a local variable before printing it

# Task 2: make the Animal constructor take an argument 'name' and add "my name is <...>" to the #hi method

# Task 3: make the animal's name accessible via a read accessor. Create an animal and prints its name

# Task 4: make the animal's name accessible via a read/write accessor. Create an animal and change its name to Frank


# TOPIC: INHERITANCE AND METHOD OVERRIDING #####################################

# Task 1: define a class Dog that inherits from Animal

# Task 2: override #hi in Dog to print 'woof'

# Task 3: have Dog#hi take a name and call Animal#hi after printing woof

# Task 3: define Dog#rap_name. For d = Dog.new(name: "Bob"); d.rap_name should return "B-Dog"


# TOPIC: MESSAGE PASSING AND METHOD_MISSING ####################################

# Task 1: write a method_missing for Dog that prints "dogs can't <method_name>"

# Task 2: if the variable 'action' is a method name as a string or symbol, call that method on a Dog object


# TOPIC: MODULES AS NAMESPACES AND MIX-INS, OPEN CLASSES #######################

# Task 1: nest the Animal class inside a module Farm

# Task 2: print the PI constant, which is in the Math module.

# Task 3: define a module Saying with an instance method say, that prints self

# Task 4: mix Saying into String and run the say method on the object "test string"


# TOPIC: BLOCKS AND YIELD, PROCS ###############################################

# Task 1: define a method salutations that prints hi, invokes its block argument with the argument 'again' and prints the result, then prints bye

# Task 2: invoke salutations with a block that takes an argument returns a string "it's great to be here <argument>"

# Task 3: define a variable that stores something like the previous block, then invoke salutations with that


# TOPIC: ITERATION: EACH, MAP ##################################################

# Task 1: print out each item in an array nums

# Task 2: from array nums, generate a new array with each number squared


# TOPIC: EXCEPTIONS ############################################################

# Task 1: raise a runtime exception

# Task 2: rescue the exception generated by 1/0 and print 'an exception happened'


# DAS ENDE #####################################################################