random utterings...: Fixed Length Random numbers in Ruby

Fixed Length Random numbers in Ruby

Chris Barnes — Wed, 09 Jan 2008 11:20:00 +0000

My latest project is almost complete and we're setting up a demo site with lots of fake data already included so I used the faker gem to generate most of it.

One issue I had that I couldn't do with the faker gem out of the box is get a fixed length random number. I need this for license numbers, credit card numbers, phone numbers and others. The faker gem does offer a random phone number but the ones in my project don't support extensions or punctuation so rather than generating the number then using string functions to strip out the stuff I didn't want, I decided to find an easier way.

I started by Googling for it assuming that someone else had already figured it out and while I'm sure its been done a hundred times before, I couldn't find it anywhere. So after much thought and digging through the ruby docs, this is what I came up with.

rand(9999999999).to_s.center(10, rand(9).to_s)

rand(9999999999) will give me a number between 0 and 9999999999. Convert it to a string and use the center method to make sure its at least 10 digits long and pad the rest with a random number from 0-9. rand(9)

If you need a number of say 7 digits in length, just change the first rand to rand(9999999) and change the center method length to 7 so it looks like this.

rand(9999999).to_s.center(7, rand(9).to_s)

Hope this is helpful to someone.

"Fixed Length Random numbers in Ruby" by Pdf search

Wed, 08 Sep 2010 12:39:36 +0000

If you are testing the actual values you have a small chance of getting a test failure, but without going too crazy it works alright. Thank for info!

"Fixed Length Random numbers in Ruby" by Mobile phone accessories

Mon, 02 Aug 2010 07:21:53 +0000

I really like the work that has gone into making the post. I will be sure to tell my blog buddies about your content keep up the good work. Thanks

"Fixed Length Random numbers in Ruby" by karloz

Wed, 15 Apr 2009 13:45:05 +0000

It helped me, thanks! :)

"Fixed Length Random numbers in Ruby" by Mark Thurgood

Wed, 25 Feb 2009 09:59:30 +0000

Come to think of it the first rand() only returns up to 9999999998 so that should be increased by one too.

"Fixed Length Random numbers in Ruby" by Mark Thurgood

Wed, 25 Feb 2009 09:57:16 +0000

Great tip! Thanks! I believe that rand(9) returns 0-8 though. Example should be: rand(9999999999).to_s.center(10, rand(10).to_s)

"Fixed Length Random numbers in Ruby" by Joe

Tue, 05 Aug 2008 15:27:05 +0000

Just what i needed, thanks.

"Fixed Length Random numbers in Ruby" by Noah Gibbs

Sun, 06 Jul 2008 00:44:09 +0000

If you want to make this a function based on length, one way to get that initial "9999999" would be the expression: ("9" * length).to_i

"Fixed Length Random numbers in Ruby" by Tinks

Sat, 05 Jul 2008 01:21:25 +0000

Very nice.. Thanks for the tip. :)