The difference between rand(1e9...1e10).to_i and rand.to_s[2..11].to_i

Question

In Ruby 2.3.0, when I do rand.to_s[2..11].to_i to insert something multiple times in a loop in the ActiveRecord, which validates length: {maximum: 10, minimum: 10}. I got an error after some iteration that the length validation failed! And when I do rand(1e9...1e10).to_i in the same scenario, it solves the problem. I want to know what's the difference between these two.

Answer 1

#rand without arguments generates a random number between 0 and 1.

This can be 0.01111111111111. to_s[2..12] then takes the first 10 digits after the decimal dot.

'01'.to_i # => 1

Hence you might get length less than 10.