if/else/elsif
a = 'hello' b = false if a p a elsif b p b else p 'ok' end
unless
unless相当于if的反向断言
unless false 'ok' end # => 'ok'
if/unless
a = 1 if a != 1 #如果a不是1 则a复制为1 b = 2 unless defined?(b) #如果b未定义 那么就定义b赋值为2
case
case a when 1 1 when /hello/ "hello world" when Array [] else 'ok' end
while
a = 0 while a < 100 do p a a += 1 end
ruby 没有++和--操作符
Iterators
for x in [1, 2, 3] do p x end [1, 2, 2].each do |x| p x end 10.times {|x| p x}
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