Ruby Programming Training Quiz #1

1. What is the first index of an array

1

0

-1

None of the above

An array's indices start with 0

Explanation

An array's indices start with 0

2. Ruby array can contain values of which type?

Integers

Floats

Characters

Any type

Strings

Ruby array may contain values of any type

Explanation

Ruby array may contain values of any type

3. What is the size of Ruby array

10

A Ruby array has no fixed size

Count

None of the above

A Ruby array has no fixed size. It is automatically incremented as elements are added at the run time.
The count is an itterator used with for loop.

Explanation

A Ruby array has no fixed size. It is automatically incremented as elements are added at the run time.
The count is an itterator used with for loop.

4. Please look at this snippet of code:

animal_sounds = {"dogs" => "bark", "elefant" => "trumpet", "lion" =>"roar", "cat" => "meow"}
def zoo(param)
        for each_animal, each_sound in param
              puts each_sound
        end
        i_go ="Enough already!"
end
my_pet_goes = zoo(animal_sounds)

What is the value of my_pet_goes variable in the snippet of code below?

Enough already!

Roar

Bark

Trumpet

None of the above

The correct answer is A - "Enough already!".
The value of my_pet_goes variable is set by return value of zoo method. Even though there is no explicit return statement, by default, the method returns the last evaluated expression, which is i_go ="Enough already!"

Explanation

The correct answer is A - "Enough already!".
The value of my_pet_goes variable is set by return value of zoo method. Even though there is no explicit return statement, by default, the method returns the last evaluated expression, which is i_go ="Enough already!"

5. What is the difference between a hash and an array in Ruby?

Hash indices can be of any type

There is no difference

The size of a hash is not fixed

The hash size is incremented dynamically

None of the above

A. This is correct answer.
B. Is the wrong answer because array indices can only be of integer type.
C. This answer is wrong because the size of both array and hash are not fixed and incremented dynamically
D. This answer is wrong. The same reason as C.

Explanation

A. This is correct answer.
B. Is the wrong answer because array indices can only be of integer type.
C. This answer is wrong because the size of both array and hash are not fixed and incremented dynamically
D. This answer is wrong. The same reason as C.

6. What is the name of key/value pair in Ruby hash?

Index

Value

Entry

Parameter

None of the above

In Ruby hash, a key/value pair is referred to as an "entry". This term is commonly used to describe the combination of a key and its corresponding value in a hash data structure. The entry allows for efficient retrieval and manipulation of data stored in the hash, where each key is unique and associated with a specific value.

Explanation

In Ruby hash, a key/value pair is referred to as an "entry". This term is commonly used to describe the combination of a key and its corresponding value in a hash data structure. The entry allows for efficient retrieval and manipulation of data stored in the hash, where each key is unique and associated with a specific value.

7. Let's create an array:
a=[12345, 23456, 34567, 98765]
Which statement will print an index of the third element of this array.

A[2]

Puts a[3]

For count in a print count if count ==2end

For count in a print a[2]end

A. Is wrong because it will not print anything.
B. Is wrong because it will print 98765
C. Is the correct answer
D. Is wrong because it will output the third element with each itteration of for loop

Explanation

A. Is wrong because it will not print anything.
B. Is wrong because it will print 98765
C. Is the correct answer
D. Is wrong because it will output the third element with each itteration of for loop

8. What is correct way to pass parameters to a block?

Block parameters are located at the beginning of the block, enclosed in square brackets and are separated by semicolon.

Block parameters are located at the beginning of the block and separated by semicolon.

None of the above

The correct answer is A - Block parameters are located at the beginning of the block, enclosed in a pipe symbols (||) and are separated by a colon.

Explanation

The correct answer is A - Block parameters are located at the beginning of the block, enclosed in a pipe symbols (||) and are separated by a colon.

9. Which statement correctly defines hash h?

H=[fish => Catfish, dog => Terrier, cat => Siamese]

H={fish => Catfish, dog => Terrier, cat => Siamese}

H=[fish - Catfish, dog - Terrier, cat - Siamese]

H=[fish => Catfish dog => Terrier cat => Siamese]

None of the above

The correct answer is E - "None of the above"
The correct answer to define such hash is h={"fish" => "Catfish", "dog" => "Terrier", "cat" => "Siamese"}

Explanation

The correct answer is E - "None of the above"
The correct answer to define such hash is h={"fish" => "Catfish", "dog" => "Terrier", "cat" => "Siamese"}

10. Let's create an array:
a=[1,2,3,4,5]
Which statement creates the following output:
[1, 2, 3, 4, 5]

Puts a[0..5]

A=[0,1,2,3,5]puts a[0..5]

Print a[1..5]

For count in aprint a[count]end

None of the above

A. Is the wrong answer because:
puts outputs one string at a time, so the elemets of an array will be separated by new line.
B. Is the same as A.
C. will print 2345
D. Is a correct answer

Explanation

A. Is the wrong answer because:
puts outputs one string at a time, so the elemets of an array will be separated by new line.
B. Is the same as A.
C. will print 2345
D. Is a correct answer

11. What makes a snippet of code into a block?

Making a method out of snippet of code turns it into a block.

None of the above

Answers C and D are correct. The block can be created by surrounding set of statements with curly brackets or with "do" and "end" words.

Explanation

Answers C and D are correct. The block can be created by surrounding set of statements with curly brackets or with "do" and "end" words.

Submit

12. Let's define a hash h.
h={"fish" => "Catfish", "dog" => "Terrier", "cat" => "Siamese"} What is the right way to refer to the second element of this hash?

H[1]

H[2]

H[dog]

H['dog']

H["dog"]

Answers D and E are correct.
Value of h[1] and h[2] is nil and value of h[dog] prodices an error ...undefined local variable or method 'dog'...

Explanation

Answers D and E are correct.
Value of h[1] and h[2] is nil and value of h[dog] prodices an error ...undefined local variable or method 'dog'...

Submit

13. What will a standard output of this code snippet be?

def print_parameters(par1, par2, par3)
       puts par1
        puts '#{par2}'
        puts "#{par3}"

end

Par1par3

Par1#{par2}par3

Par1 par2 par3

No output

None of the above

The correct answer is D. There will be no output, since the method print_parameters was not called yet. The statements inside the method are executed only when the method is called.

Explanation

The correct answer is D. There will be no output, since the method print_parameters was not called yet. The statements inside the method are executed only when the method is called.

14. What will a standard output of this code snippet be?
name = "Alva"
print name if name = 'Ary ' ; print "Alva" ;

AryAlva

Ary Alva

Nothing

AryAlva

None of the above

The correct answer is C - there will be no output in a standard out stream. This is because the last line of the question ends with a semicolon. This semicolon signifies that there will be a valid statement after it.

Explanation

The correct answer is C - there will be no output in a standard out stream. This is because the last line of the question ends with a semicolon. This semicolon signifies that there will be a valid statement after it.

15. Let's define a hash h.
h={"fish" => "Catfish", "dog" => "Terrier", "cat" => "Siamese"}
Which for loop produces an error?

For animal in h puts animalendputs h['cat']

For h in h puts hend

For h in h puts hendputs h['cat']

Correct answer is E, it produces an error "can't convert String into Integer". This happens because after for loop is executed, variable h is redefined as two dimensional array. So notation h['cat'] is not legal, since indices of an array can only be numerical.

Explanation

Correct answer is E, it produces an error "can't convert String into Integer". This happens because after for loop is executed, variable h is redefined as two dimensional array. So notation h['cat'] is not legal, since indices of an array can only be numerical.