How to generate a random number in Crystal?

Question

In Crystal, how can I generate a random number?

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Using Python, I can simply do the following to generate a random integer between 0 and 10:

from random import randint
nb = randint(0, 10)

Answer 1

Solution 1 - Use the Random module

Random Integer

Random.new.rand(10)      # >= 0 and < 10
Random.new.rand(10..20)  # >= 10 and < 20

Random Float

Random.new.rand(1.5)          # >= 0 and < 1.5
Random.new.rand(6.2..18.289)  # >= 6.2 and < 18.289

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Solution 2 - Use the top-level method rand

As pointed out by @Jonne in the comments, you can directly use the top-level method rand that calls the Random module:

Random Integer

rand(10)      # >= 0 and < 10
rand(10..20)  # >= 10 and < 20

Random Float

rand(1.5)          # >= 0 and < 1.5
rand(6.2..18.289)  # >= 6.2 and < 18.289

Answer 2

Even shorter is rand:

# ints
rand(10)
rand(10..20)

# floats
rand(1.5)
rand(6.2..18.289)