Checking if a variable is an integer

Question

Does Rails 3 or Ruby have a built-in way to check if a variable is an integer?

For example,

1.is_an_int #=> true
\"dadadad@asdasd.net\".is_an_int          


        

Answer 1

If you're uncertain of the type of the variable (it could be a string of number characters), say it was a credit card number passed into the params, so it would originally be a string but you want to make sure it doesn't have any letter characters in it, I would use this method:

    def is_number?(obj)
        obj.to_s == obj.to_i.to_s
    end

    is_number? "123fh" # false
    is_number? "12345" # true

@Benny points out an oversight of this method, keep this in mind:

is_number? "01" # false. oops!