chapter2.md

조건문

if/else/elsif/end

if x < y  # Assumes x and y are defined
 puts "x is less than y!"
elsif x > y
 puts "x is greater than y!"
else
 puts "x equals y!"
end

expression if boolean

unless/else/end

unless hungry
 # Write some 
else
 # Have some noms
end

expression unless boolean

case/when/else/end

case language
when "JS"
  	puts "Websites!"
when "Python"
  	puts "Science!"
when "Ruby"
  	puts "Web apps!"
else
  	puts "I don't know!"
end

case language
  when "JS" then puts "Websites!"
  when "Python" then puts "Science!"
  when "Ruby" then puts "Web apps!"
  else puts "I don't know!"
end

ternary conditional expression

boolean ? Do this if true: Do this if false

puts 3 < 4 ? "3 is less than 4!" : "3 is not less than 4."

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Comparators

relational operator

• == 와 = 의 차이점

==는 같다는 표현으로 비교를 할 때 사용된다. =는 대입을 할 때 사용된다.

x = 2
y = 2
if x == y
 print "x and y are equal!"
end

• != : not equal
• < : less than
• <= : less than or equal to
• > : greater than
• >= : greater than or equal to

logical operator

• && : and (둘다 true 이면 true)
• || : or (둘중 하나만 true 이면 true)
• ! : not (반대)

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