# \[noob question\] convert 7 in 07 **URL:** \ **Category:** Ruby\ **Created:** [April 22, 2009, 12:38pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157 "2009-04-22T12:38:56Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 12:38pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/1 "2009-04-22T12:38:56Z")
Hi, I would like to display numbers with a 0 before when there is only one char. For exemple if I gets the number 4, I would like to return 04. After looking methods on [http://www.ruby-doc.org/core/classes/Fixnum.html](http://www.ruby-doc.org/core/classes/Fixnum.html), I don’t see how to process. Of cours it is possible to convert a number into string and after add a 0, but it’s not very friendly. Thanks for ideas ---
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 12:45pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/2 "2009-04-22T12:45:00Z")
2009/4/22 Paul A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > I would like to display numbers with a 0 before when there is only one > char. > For exemple if I gets the number 4, I would like to return 04. > > After looking methods on > [http://www.ruby-doc.org/core/classes/Fixnum.html](http://www.ruby-doc.org/core/classes/Fixnum.html), I don’t see how to > process. Of cours it is possible to convert a number into string and > after add a 0, but it’s not very friendly. Please look up sprintf, printf and String#%. Cheers robert ---
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 12:52pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/3 "2009-04-22T12:52:14Z")
counter = 1; sprintf("%02d", counter) # =\> “01” In general, the ruby String class is much better than Int class - because Strings are like everywhere in ruby. I believe Matz once said that the String class was most work (or devoured most manhours when he worked on ruby initially) ---
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 1:00pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/4 "2009-04-22T13:00:52Z")
> And keep in mind that you will have to convert to string anyway, because while 07 is fine 08 and 09 are illegal in Ruby—it treats numbers with leading zero as octal numbers: > > 7 > > =\> 7 > > > 07 > > =\> 7 > > > 8 > > =\> 8 > > > 08 > > SyntaxError: (irb):4: Invalid octal digit from /usr/local/bin/irb:12:in > > `’ Regards, Rimantas ---
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 1:33pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/5 "2009-04-22T13:33:10Z")
irb(main):001:0\> n=7 =\> 7 irb(main):002:0\> “%02d” % n =\> “07” — On Wed, 4/22/09, Paul A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: From: Paul A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Subject: [noob question] convert 7 in 07 To: “ruby-talk ML” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Date: Wednesday, April 22, 2009, 6:39 AM Hi, I would like to display numbers with a 0 before when there is only one char. For exemple if I gets the number 4, I would like to return 04. After looking methods on [http://www.ruby-doc.org/core/classes/Fixnum.html](http://www.ruby-doc.org/core/classes/Fixnum.html), I don’t see how to process. Of cours it is possible to convert a number into string and after add a 0, but it’s not very friendly. Thanks for ideas ---
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 1:50pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/6 "2009-04-22T13:50:47Z")
On Apr 22, 6:58 am, “DanDiebolt.exe” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > To: “ruby-talk ML” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > Date: Wednesday, April 22, 2009, 6:39 AM > > Hi, > > I would like to display numbers with a 0 before when there is only one > char. > For exemple if I gets the number 4, I would like to return 04. > > After looking methods onhttp://www.ruby-doc.org/core/classes/Fixnum.html, I don’t see how to > process. Dan’s suggestion is the simplest. But I want to point out that you can add a Fixnum method yourself, if you are so inclined: class Fixnum def to\_formatted\_s “%02d” % self end end puts 7.to\_formatted\_s ---
**Author:** ![judge](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de0a6/32.png) [@judge](https://www.ruby-forum.com/u/judge)\ **Post date:** [April 22, 2009, 2:33pm UTC](https://www.ruby-forum.com/t/noob-question-convert-7-in-07/166157/7 "2009-04-22T14:33:41Z")
> \*'s suggestion is the simplest Well I just picked it up on one of the n-tips for ruby lists. This isn’t the list I originally studied but it does contain the same idea in tip #9: 1. Pretty print strings decimals. The format descriptors are pretty much similar to those used in C’s printf so I won’t go into details. my\_string = “%01d %06d %02d” % [type, code, age] [http://alexbrie.net/2002/10-ruby-programming-tips-you-should-already-know/](http://alexbrie.net/2002/10-ruby-programming-tips-you-should-already-know/) These lists are an invaluable resource to improve your code.