Mark A. Nicolosi Mark A. Nicolosi - 1 year ago 85
Ruby Question

How to get a random number in Ruby

How do I generate a random number between


Answer Source

What is wrong with rand(range)?

From Ruby Random Numbers:

If you needed a random integer to simulate a roll of a six-sided die, you'd use: 1 + rand(6). A roll in craps could be simulated with 2 + rand(6) + rand(6).

Finally, if you just need a random float, just call rand with no arguments.

As Marc-André Lafortune mentions in his answer below (go upvote it), Ruby 1.9.2 has its own Random class (that Marc-André himself helped to debug, hence the 1.9.2 target for that feature).

For instance, in this game where you need to guess 10 numbers, you can initialize them with:{ 20 + Random.rand(11) } 
#=> [26, 26, 22, 20, 30, 26, 23, 23, 25, 22]


This is why the equivalent of would be 20 + Random.rand(11), since Random.rand(int) returns “a random integer greater than or equal to zero and less than the argument.” 20..30 includes 30, I need to come up with a random number between 0 and 11, excluding 11.