# Uniuq no **URL:** \ **Category:** Ruby\ **Created:** [February 14, 2009, 10:21am UTC](https://www.ruby-forum.com/t/uniuq-no/160316 "2009-02-14T10:21:17Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 14, 2009, 10:21am UTC](https://www.ruby-forum.com/t/uniuq-no/160316/1 "2009-02-14T10:21:17Z")
I want to create new unique id in ruby.I have used the following coding.But I don’'t know whether it works perfectly or not. t = Time.new p “%10.5f” % t.to\_f does it give unique value always.I you know some other way ,please say to create unique id . ---
**Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 14, 2009, 10:41am UTC](https://www.ruby-forum.com/t/uniuq-no/160316/2 "2009-02-14T10:41:50Z")
Vetrivel V. wrote: > I want to create new unique id in ruby.I have used the following > coding.But I don’'t know whether it works perfectly or not. > > t = Time.new > p “%10.5f” % t.to\_f > > does it give unique value always. This might be better: d = Time.new t = d.to\_f puts t r = rand puts r p\_id = $$ puts p\_id new\_id = t + 10000000 \* r + 10000000 \* p\_id p new\_id ---
**Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 14, 2009, 4:21pm UTC](https://www.ruby-forum.com/t/uniuq-no/160316/3 "2009-02-14T16:21:14Z")
7stud – wrote: > Vetrivel V. wrote: > > > I want to create new unique id in ruby.I have used the following > > coding.But I don’'t know whether it works perfectly or not. > > > > t = Time.new > > p “%10.5f” % t.to\_f > > > > does it give unique value always. > > This might be better: > > d = Time.new > t = d.to\_f > puts t > > r = rand > puts r > > p\_id = $$ > puts p\_id > > new\_id = t + 10000000 \* r + 10000000 \* p\_id > p new\_id Be a little careful with this, floats are not very precise, (see: [Bug in converting float to int? - Ruby - Ruby-Forum](http://www.ruby-forum.com/topic/178503) ) and this could lead to some duplication. irb(main):001:0\> a = (10.12 \* 100).to\_i =\> 1011 irb(main):002:0\> b = (10.11 \* 100).to\_i =\> 1011 irb(main):003:0\> a == b =\> true While this really shouldn’t be a problem with this scheme, big decimal might be safer… (see: [http://www.ruby-doc.org/stdlib/libdoc/bigdecimal/rdoc/classes/BigDecimal.html](http://www.ruby-doc.org/stdlib/libdoc/bigdecimal/rdoc/classes/BigDecimal.html) ) ---
**Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 14, 2009, 4:23pm UTC](https://www.ruby-forum.com/t/uniuq-no/160316/4 "2009-02-14T16:23:00Z")
Time.new.to\_i.to\_s\<\ **Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 25, 2009, 3:16pm UTC](https://www.ruby-forum.com/t/uniuq-no/160316/5 "2009-02-25T15:16:35Z") - Vetrivel V. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I want to create new unique id in ruby.I have used the following > coding.But I don’'t know whether it works perfectly or not. > > t = Time.new > p “%10.5f” % t.to\_f > > does it give unique value always.I you know some other way ,please say > to create unique id . UUID¹ is a standard way of constructing unique identifiers, and a Ruby library² exist already, so unless you require the identifiers to be integers, I suggest you use that. [1] [Universally unique identifier - Wikipedia](http://en.wikipedia.org/wiki/UUID) [2] [http://wiki.github.com/assaf/uuid](http://wiki.github.com/assaf/uuid) – Lars H. “If anyone disagrees with anything I say, I am quite prepared not only to retract it, but also to deny under oath that I ever said it.” -Tom Lehrer ---
**Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 14, 2009, 5:07pm UTC](https://www.ruby-forum.com/t/uniuq-no/160316/6 "2009-02-14T17:07:39Z")
Vetrivel V. wrote: > I want to create new unique id in ruby.I have used the following > coding.But I don’'t know whether it works perfectly or not. > > t = Time.new > p “%10.5f” % t.to\_f > > does it give unique value always.I you know some other way ,please say > to create unique id . How about something like this… count = 0 t = Time.now.to\_s 10000.times { if( t == Time.now.to\_s) count = count + 1 else count = 0 t = Time.now.to\_s end uniqid = t + “.” + count.to\_s puts uniqid } That way you don’t have to worry about rounding, or the possibility that the same random number might come up twice. The only real problem with this scheme is that on a very fast computer it might be possible to generate more ids each second than will fit in an Int. But, Bignum might be able to help there… ---
**Author:** ![vetrivel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/dc4da7/32.png) [@vetrivel](https://www.ruby-forum.com/u/vetrivel)\ **Post date:** [February 25, 2009, 4:43pm UTC](https://www.ruby-forum.com/t/uniuq-no/160316/7 "2009-02-25T16:43:15Z")
On Feb 25, 2009, at 3:14 PM, Lars H. wrote: > > to create unique id . > > “If anyone disagrees with anything I say, I am quite prepared not > only to > retract it, but also to deny under oath that I ever said it.” -Tom > Lehrer UUIDs can also be notated in an integer representation. It’s just a bit long. There are multiple libraries, this example uses the gem uuidtools: > > UUID.timestamp\_create.to\_i > > 227941543066369752189048382045440381927 They are the best way to choose. Regards, Florian – Florian G. smtp: removed\_email\_address@domain.invalid jabber: removed\_email\_address@domain.invalid gpg: 533148E2