Ruby Symbols/Keywords/Data Types

Question 1

alias

Answer 1

Creates an alias for an existing method, operator, or global variable.

Examples:

alias new old
alias :new :old
alias :new, :old

Question 2

and

Answer 2

Logical operator; same as &&, except “and” has lower precedence.

Question 3

BEGIN

Answer 3

Code, enclosed in { and }, that will run before the program runs.

Question 4

begin

Answer 4

Begins a code block or group of statements; closes with “end” (not to be confused with BEGIN and END).

Question 5

break

Answer 5

Terminates a “while” or “until” loop, or a method inside a block.

Question 6

case

Answer 6

Compares an expression with one or more matching “when” clauses; closes with end. Can be used with or without a value to match against.

Example:
print "Enter a string: "
some_string = gets.chomp
case
when some_string.match(/\d/)
  puts 'String has numbers'
when some_string.match(/[a-zA-Z]/)
  puts 'String has letters'
else
  puts 'String has no numbers or letters'
end

Question 7

class

Answer 7

Defines a class; closes with end.

Question 8

def

Answer 8

Defines a method; closes with end.

Question 9

defined?

Answer 9

Determines if a variable, method, super method, or block exists.

Question 10

do

Answer 10

Begins a block and executes code in that block; closes with end.

Question 11

else

Answer 11

Executes if previous conditional from “if”, “elsif”, “unless”, or “when”, is not true.

Question 12

elsif

Answer 12

Executes if previous conditional from “if” or “elsif” is not true.

Question 13

END

Answer 13

Code, enclosed in { and }, to run when the program ends.

Question 14

end

Answer 14

Ends a code block (group of statements) starting with “begin”, “def”, “do”, “if”, etc.

Question 15

ensure

Answer 15

Always executes at block termination; use after last rescue.

Example:
begin
# something which might raise an exception
rescue SomeExceptionClass => some_variable
# code that deals with some exception
else
# code that runs only if no exception was raised
ensure
# ensure that this code always runs, no matter what
end

Question 16

false

Answer 16

Logical or Boolean false, instance of FalseClass.

Question 17

for

Answer 17

Begins a for loop; used with in.

Question 18

if

Answer 18

Executes code block if true. Closes with end.

Question 19

module

Answer 19

Defines a module; closes with end.

Question 20

next

Answer 20

Jumps before a loop’s conditional.

Question 21

nil

Answer 21

Empty, uninitialized variable, or invalid, but not the same as zero; object of NilClass.

Question 22

not

Answer 22

Logical operator; same as “!”

Question 23

or

Answer 23

Logical operator; same as “||”, except “or” has lower precedence.

Question 24

redo

Answer 24

Jumps after a loop’s conditional.

Question 25

rescue

Answer 25

Evaluates an expression after an exception is raised; used before ensure.

Question 26

retry

Answer 26

Repeats a method call outside of rescue; jumps to top of block (begin) if inside rescue.

Question 27

return

Answer 27

Returns a value from a method or block. May be omitted.

Question 28

self

Answer 28

Current object (invoked by a method).

Question 29

super

Answer 29

Calls method of the same name in the superclass. The superclass is the parent of this class.

Question 30

then

Answer 30

A continuation for if, unless, and when. May be omitted.

Question 31

true

Answer 31

Logical or Boolean true, instance of TrueClass.

Question 32

undef

Answer 32

Makes a method in current class undefined.

Question 33

unless

Answer 33

Executes code block if conditional statement is false.

Question 34

until

Answer 34

Executes code block while conditional statement is false.

Question 35

when

Answer 35

Starts a clause (one or more) under case.

Question 36

while

Answer 36

Executes code while the conditional statement is true.

Question 37

yield

Answer 37

Executes the block passed to the method.

Question 38

\a

Answer 38

Bell or alert.

Question 39

\b

Answer 39

Backspace.

Question 40

\f

Answer 40

Formfeed.

Question 41

\n

Answer 41

Newline.

Question 42

\r

Answer 42

Carriage return.

Question 43

\t

Answer 43

Tab.

Question 44

\v

Answer 44

Vertical tab.

Question 45

\\

Answer 45

Backslash

Question 46

\'

Answer 46

Single quote

Question 47

\"

Answer 47

Double quote

Question 48

: :

Answer 48

Resolution operator. Used to resolve the scope of a constant/static symbol.

Question 49

[ ]

Answer 49

Array

Question 50

* *

Answer 50

Exponent

Question 51

*

Answer 51

Multiplication

Question 52

/

Answer 52

Division

Question 53

%

Answer 53

Modulus; returns remainder

Question 54

+

Answer 54

Addition

Question 55

-

Answer 55

Subtraction

Question 56

<<

Answer 56

Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.

Question 57

>>

Answer 57

Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.

Question 58

&

Answer 58

Binary AND

Question 59

|

Answer 59

Binary OR

Question 60

>

Answer 60

Greater than

Question 61

>=

Answer 61

Greater than or equal to

Question 62

<

Answer 62

Less than

Question 63

<=

Answer 63

Less than or equal to

Answer 64

Combined comparison operator. Returns 0 if first operand equals second, 1 if first operand is greater than the second and -1 if first operand is less than the second.

Question 65

==

Answer 65

Is equal to

Question 66

===

Answer 66

Used to test equality within a when clause of a case statement.

Question 67

!=

Answer 67

Not equal to

Question 68

=~

Answer 68

Match string to regular expression.

Question 69

&&

Answer 69

Logical AND

Question 70

| |

Answer 70

Logical OR

Question 71

. .

Answer 71

Creates a range from start point to end point; inclusive.

Question 72

. . .

Answer 72

Creates a range from start point to end point; exclusive.