Ruby Quiz - 11.2.2021

Question 1

a = [[4, [5, 8]]].How will you extract the inner array value 8?

Answer 1

a.dig(0, 1, 1)

Question 2

Which method will merge elements of curremt array with corresponding elements from each argument.(index wise)

Answer 2

a = [ 4, 5, 6 ]
b = [ 7, 8, 9 ]

[1, 2, 3].zip(a, b) #=> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]

Question 3

How will you make a new copy of a current hash?

Answer 3

h.clone

Question 4

Which method rebuilds the hash based on the current hash values for each key. If values of key objects have changed since they were inserted?

Answer 4

rehash method will reindex hash.
a = [ "a", "b" ]
c = [ "c", "d" ]
h = { a => 100, c => 300 }
h[a] #=> 100
a[0] = "z"
h[a] #=> nil
h.rehash #=> {["z", "b"]=>100, ["c", "d"]=>300}
h[a] #=> 100

Question 5

differentiate - “hex’ and “oct” methods in String

Answer 5

hex - Treats leading characters from str as a string of hexadecimal digits

“0x0a”.hex #=> 10
“-1234”.hex #=> -4660

oct-Treats leading characters of str as a string of octal digits

“123”.oct #=> 83
“-377”.oct #=> -255

Question 6

Which method is used to check if the string is invalid byte sequence then replace invalid bytes with given replacement character,

Answer 6

scrub method

“abc\u3042\x81”.scrub(“”) #=> “abc\u3042”

Question 7

Is everything in Ruby an object?

Answer 7

Methods are not objects. Blocks are not objects. Keywords are not objects. However, there exist Method objects and Proc objects, and some keywords refer to objects.

Question 8

What are the subclasses of numeric datatype?

Answer 8

Integer,Float,BigDecimal,Complex,Rational

Question 9

if a symbol (say :Friend) is a constant in one context, a method in another, and a class in a third, that :ruby will be the same object in all three contexts. True or false?

Answer 9

module One
  class Friend
  end
  $f1 = :Friend
end
module Two
  Fred = 1
  $f2 = :Friend
end
def Friend()
end
$f3 = :Friend
$f1.object_id   #=> 2514190
$f2.object_id   #=> 2514190
$f3.object_id   #=> 2514190

Question 10

What does “cycle” method will do in an array?

Answer 10

a.cycle {|x| puts x} # print, a, b, c, a, b, c,.. forever.

Question 11

How can you do chain push in an array?

Answer 11

a = []

a &laquo_space;1 &laquo_space;2 &laquo_space;3

Question 12

What are the mehods to check hash keys?

Answer 12

Hash#has_key?, Hash#include?, Hash#member?

Question 13

Is ther any class in the name 
"Boolean" ? What are the classes that support boolean data type?

Answer 13

No,True class, flase class

Question 14

What “quo” method will do in Rational?

Answer 14

It will perform division

Question 15

Explain pred and succ methods in Numeric?

Answer 15

n. pred will print preceeder

n. succ will print successor

Question 16

How to display the inbetween values in a range?

Answer 16

entries, to_a

Question 17

difference between last and max methods in Range?

Answer 17

1. .10.last= “10”

1. ..10.max = “9”

Question 18

What each_pair method will do? Which class it belongs to?

Answer 18

take the pair values from a hash. Hash class

Question 19

Can case statement be assigned to any variable?

Answer 19

yes. This value can be assigned to a variable preceding the case statement.

happy = case

when …

end

puts happy

Question 20

How can you resolve name conflict(same name in mixin modules) in modules?

Answer 20

alias_method.

module Happy

	def expression
		return "smiling"
	end
	alias happyexpression expression
end