控制流 / 循环
"each"循环
"for-in"循环
"each_with_index"循环
"while"循环
"do-while"循环
"until"循环
"upto"循环
"step"循环
"times"循环
无限循环
sum10 =
0
(
1
.
.10
).
each
do
|v|
sum10 += v
end
# sum10 is 55
puts
"sum10 is
#{sum10}
"