General

Question 1

What is a comment in Ruby code?

Answer 1

from # to end of line

Question 2

A Ruby program is a sequence of…

Answer 2

expressions

Question 3

How do you terminate an expression?

Answer 3

with a ; or end-of-line

Question 4

Can an expression go beyond end-of-line?

Answer 4

Yes; if it is parsed as incomplete, parsing continues on next line

Question 5

Is there a way to force an expression to run past end-of-line unconditionally?

Answer 5

Yes, by ending the line with a backslash \

Question 6

What are the basic Ruby data types?

Answer 6

numbers, strings, ranges, regexes, symbols, arrays, hashes (and files?)

Question 7

Can a large integer be broken up for readability?

Answer 7

Yes, with underscores, e.g. 1_000_000

Question 8

How is a literal hexadecimal value denoted?

Answer 8

With “0x”, C style, e.g. 0xffff

Question 9

How is a floating-point value expressed

Answer 9

C style, e.g. 1.2e-3

Question 10

How is a literal octal value expressed

Answer 10

With “0” prefix, C style, e.g. 0377

Question 11

How is a literal binary value expressed?

Answer 11

With “0b”, e.g. 0b01011

Question 12

How is the literal value of an ASCII character expressed?

Answer 12

With a “?” prefix and no quotes, e.g. ?a

Question 13

How is the literal value of an ASCII control character expressed?

Answer 13

Prefixed with “?\C-“, e.g. ?\C-a

Question 14

How is the literal value of a “meta” character expressed?

Answer 14

Prefixed with “?\M-“, e.g. ?\M-a

Question 15

What is the simplest way to express strings (non-interpolated, no escaping)?

Answer 15

Single quoted, e.g. ‘string’

Question 16

What is the simplest way to express an interpolated string?

Answer 16

Double quoted, e.g. “value of #{variable}”

Question 17

Can an interpolated string use C-style backslash characters?

Answer 17

Yes (e.g. “\n” will be a newline)

Question 18

Can a non-interpolated string use C-style backslash characters?

Answer 18

No (e.g. ‘\n’ will literally be backslash + n)

Question 19

How else can a non-interpolated string be quoted?

Answer 19

%q(string)

Question 20

How can an interpolated string be quoted without quote marks?

Answer 20

%Q(string) or %(string)

Question 21

What is the simplest way to make a string a command to be executed in the shell?

Answer 21

Quoted with backticks, e.g. cat /etc/passwd

Question 22

How else can a shell-command string be quoted

Answer 22

%x(echo Hello)

Question 23

Can %-style strings be quoted any other way besides parentheses?

Answer 23

Yes, with matching pairs e.g. %q[string], %Q{string}, %x<echo string>; or any single char twice, e.g. %@string@, %Q!string!, %x,echo string,