ruby

ruby的if else如何写：

if x < 10
    puts "Below 10"
elsif x > 20
    puts "Over 20"
else
    puts "10-20"
end

另一种写法

puts "this is kevin" if name == "kevin"

boolean ? code1 : code2

case test_value
when value
 ...
when value
...
else
....
end

流程控制：
break = Teminate the whole loop
next = Jump to the next loop
redo = Redo this loop
retry = Start the whole loop over

break例子：

x = 0
loop do 
    x += 2
    break if x >= 20
    puts x
end

next例子

loop do 
    x += 2
    break if x >= 20
    next if x == 6
    puts x
end

while例子
while boolean
....
end

until boolean
...
end
  
Iterator：

5.times do
    puts "Hello"
end

5.times {puts "Hello"}

1.upto(5) {puts "Hello"}

5.downto(1) {puts "hello"}

(1..5).each{puts "Hello"}

1.upto(5) do |i|
    puts "Hello" + i.to_s
end

fruits = ['banana', 'apple', 'pear']
fruits.each do |fruit|
    puts fruit.capitalize
end

for fruit in fruits
    puts fruit.capitalize
end

array = [1,2,3]
array.each {|num| puts num * 20}