Question

We can do this in Java and similar languages:

for (int i=0, int j=3; i<=2 && j<=5;i++,j++){
    do some repetive task until the condition becomes false...
}

How might one keep these two conditions based on two different sets (suppose two
arrays whose indexes can be used as i and j) in condition block?

Answer 1

explicit iteration is kinda looked down upon in ruby as poor expression of thought. Usually there is a better way to achieve the desired goal.

That said, here’s is best way I know of to iterate many variables:

i, j, k = 0, 3, 7
while i <= 2 && j <= 5 && k <= 100

  # code here

  i, j, k = [i, j, k].map(&:next)
end

You can also do it a little messier

i, j = -1, 2
while( (i += 1) <= 2 && (j += 1) <= 5 )

  # code here

end 

Edit: If you want to go from 0 to 2, and 3 to 5, this works:

(3..5).each_with_index do |j, i|
  # code
end