使用范围类而不是fixnum的红宝石for循环？

Question

for i in [0..4] do
  puts i + 1
end

undefined method `+' for 0..4:Range (NoMethodError)

Why is it not treating each number in the range as a fixnum within the loop?

Answer 1

[0..4] is actually array with one range element, the same as [(0..4)] . You need to change it to (0..4) .

Answer 2

Write instead:

for i in 0..4 do

Otherwise you don't have a range, you have an array containing 1 range.

Answer 3

There are different ways to achive a goal:

0.upto(4) { |i|
  puts i
}

0.step(4, 1) { |i|
  puts i
}

5.times { |i| # 5 for inclusive
  puts i
}

for i in 0..4
  puts i
end

Everything will output:

# ⇒ 0
# ⇒ 1
# ⇒ 2
# ⇒ 3
# ⇒ 4

Hope it helps.