Ruby Programming Training Quiz #2

1. Which statement uses an instance variable?

Sound="roar"

@@sound="roar"

@sound="roar"

Puts #{sound}

None of the above

The correct answer is C - The instance variable starts with a single at-sign

Explanation

The correct answer is C - The instance variable starts with a single at-sign

2. What is the right way to create subclass Bird based on the calss Animal?

Class Bird > Animal

Class Bird < Animal

Class Bird extends Animal

Calss Bird

None of the above

The correct answer is B - calss Bird

Explanation

The correct answer is B - calss Bird

3. What is the output of this statement
a= 3_1_4_1_5_9_2_6; puts a

3_1_4_1_5_9_2_6

3 1 4 1 5 9 2 6

31415926

None of the above

The correct answer is C. Underscore characters are ignored in the digit string.

Explanation

The correct answer is C. Underscore characters are ignored in the digit string.

4. Which of these statements is false?

Enumeratable class doesn't have iterator methods

You can not write your own iterator method

Array class doesn't have iterators methods

Hash class doesn't have iterators methods

All of the above

The correct answer is E - All of the above statements are false.

Explanation

The correct answer is E - All of the above statements are false.

5. A=5
b=7
Which of the statements below is illegal in Ruby?

A+b if TRUE

A+b if false

True=a+b

A + b if a==true

None of the above

The correct answer is C. The true is a spacial constant in Ruby and we can not assign any value to constants like self, true, false, nil, __FILE__, __LINE__

Explanation

The correct answer is C. The true is a spacial constant in Ruby and we can not assign any value to constants like self, true, false, nil, __FILE__, __LINE__

6. Which statement prints the objec animal?

Animal.to_s

P animal

Puts animal.inspect

None of the above

B and C are both correct answers. The statement p animal is equivalent of the statement puts animal.inspect

Explanation

B and C are both correct answers. The statement p animal is equivalent of the statement puts animal.inspect

Submit

7. Which statement below contains a symbol?

H={:bird=>'fly', :horse=>'gallop', :snake=>'snake'}

:snake.to-s

H={bird:=>'fly', horse:=>'gallop', snake:=>'snake'}

Snake:.to_s

None of the above

The correct answers are A and B

Explanation

The correct answers are A and B

Submit

8. What is the correct way of defining a method with variable number of parameters?

Def my_method(param_all*)

Def my_method(*param_all)

Def my_method(first_param, *param_all)

Def my_method(*first_param, *param_all)

Def my_method(*first_param, param_all*)

The correct answers are B and C - The variable number of parameters in a method is denoted by prefixing the last parameter with an asterisk.

Explanation

The correct answers are B and C - The variable number of parameters in a method is denoted by prefixing the last parameter with an asterisk.

Submit

9. Which statement prints the Ruby interpreter load path, which is used to search for files listed with the "require" directive?

Puts ::

Puts $$

Puts $:

Puts @@

None of the above

The correct answer is C - the statement puts $: prints out Ruby interpreter load path.

Explanation

The correct answer is C - the statement puts $: prints out Ruby interpreter load path.

10. Which identifyer listed below can be used as a name of a local variable?

Alias

#alias

%alias

None of the above

The correct answer is B. Ruby is a case sensitive language, so Alias is not the same a a key word alias. #alias is a comment and %alias is illegal, since alias is a keyword in Ruby and can not be used as a delimiter which is expected after %.

Explanation

The correct answer is B. Ruby is a case sensitive language, so Alias is not the same a a key word alias. #alias is a comment and %alias is illegal, since alias is a keyword in Ruby and can not be used as a delimiter which is expected after %.

11. What is the right way to continue Ruby statement on a second line?

Use a semicolon at the end of the first line

Use a backslash at the end of the first line

Break line at an operator like + or - or break after semicolon between method parameters

None of the above

The coreect answers are B and C

Explanation

The coreect answers are B and C

Submit

12. Class Animal is defined in the module Zoo which is stored in the file zoo_file.rb
Which statement is true?

To use the code from module Zoo you have to include the statementrequire 'zoo_file'

To use the code from module Zoo you have to start with the statement "include Zoo"

Ruby code can be grouped into modules

The statements A, D and E are correct. Ruby code can be grouped in the module. To use classes defined in the module, the statement require 'module_file_name' has to be present. To allow using the class methods without ModuleName::, the statement "include ModuleName" has to be included in the code after the statement "require 'module_file'" and before any methods are used.

Explanation

The statements A, D and E are correct. Ruby code can be grouped in the module. To use classes defined in the module, the statement require 'module_file_name' has to be present. To allow using the class methods without ModuleName::, the statement "include ModuleName" has to be included in the code after the statement "require 'module_file'" and before any methods are used.

Submit

13. Which statement allows to modify instance variable @sound?

Attr @sound, TRUE

Attr :sound, TRUE

Attr_reader :sound

Attr_accessor :sound

Attr_writer :sound

The correct answers are B, D and E. The accessor which allows to modify an instance variable @sound can be any of these three statements:
attr :sound, TRUE
attr_accessor :sound
attr_writer :sound

Explanation

The correct answers are B, D and E. The accessor which allows to modify an instance variable @sound can be any of these three statements:
attr :sound, TRUE
attr_accessor :sound
attr_writer :sound

Submit

14. What is the right way to define "Here document" string in Ruby?

My_string=