# Simple string operation **URL:** \ **Category:** Ruby\ **Created:** [July 10, 2007, 4:54am UTC](https://www.ruby-forum.com/t/simple-string-operation/108968 "2007-07-10T04:54:06Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 10, 2007, 4:54am UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/1 "2007-07-10T04:54:06Z")
seqNo = File.basename("/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV",".\*")[-1,3].to\_s seqNo = “-” + seqNo+ “.xx.m” puts "seqNo: #{seqNo} " # \>\> seqNo: -4.xx.m but I want it to be -004.xx.m. In other words I want the leading zeros. I didn’t even think the .to\_s should be necessary, but tried it in desperation. Thanks Newbie (but you already figured that out by the question). ---
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 10, 2007, 5:35am UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/2 "2007-07-10T05:35:28Z")
On 7/9/07, 12 34 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > seqNo = > File.basename(“/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV”,“.\*”)[-1,3].to\_s > seqNo = “-” + seqNo+ “.xx.m” > puts "seqNo: #{seqNo} " # \>\> seqNo: -4.xx.m > > but I want it to be -004.xx.m. In other words I want the leading zeros. Maybe you want [-3,3] instead of [-1,3]? Todd ---
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 10, 2007, 5:53am UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/3 "2007-07-10T05:53:03Z")
Todd B. wrote: > On 7/9/07, 12 34 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > seqNo = > > File.basename(“/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV”,“.\*”)[-1,3].to\_s > > seqNo = “-” + seqNo+ “.xx.m” > > puts "seqNo: #{seqNo} " # \>\> seqNo: -4.xx.m > > > > but I want it to be -004.xx.m. In other words I want the leading zeros. > > Maybe you want [-3,3] instead of [-1,3]? Maybe I do. Thank you ---
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 10, 2007, 6:03am UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/4 "2007-07-10T06:03:30Z")
On 10 Jul 2007, at 11:54, 12 34 wrote: > desperation. > > Thanks Your use of String#[] is wrong: -------------------------------------------------------------- String#[] Element Reference—If passed a single +Fixnum+, returns the code of the character at that position. If passed two +Fixnum+ objects, returns a substring starting at the offset given by the first, and a length given by the second. So [-1,3] gives you a string starting at the last character that is 3 characters long. You run off the end of the string before it gets to 3 characters, so it ends up just being the last character - 4. I wonder if Ruby shouldn’t raise an IndexError in that case. Replace it with [-4,4] to get what you want (I think) - the last 4 characters. As you mention, the .to\_s is unnecessary. seqNo = File.basename("/Volumes/MINOLTA1/DCIM/100MLT16/ PICT0004.MOV",".\*")[-4,4] seqNo = “-#{seqNo}.xx.m” Alex G. Bioinformatics Center Kyoto University ---
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 10, 2007, 8:27am UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/5 "2007-07-10T08:27:39Z")
2007/7/10, Todd B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > On 7/9/07, 12 34 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > seqNo = > > File.basename(“/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV”,“.\*”)[-1,3].to\_s > > seqNo = “-” + seqNo+ “.xx.m” > > puts "seqNo: #{seqNo} " # \>\> seqNo: -4.xx.m > > > > but I want it to be -004.xx.m. In other words I want the leading zeros. > > Maybe you want [-3,3] instead of [-1,3]? Or seqNo = File.basename(fname)[/\d+/] cheers robert ---
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 11, 2007, 3:45pm UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/6 "2007-07-11T15:45:52Z")
On Jul 9, 8:54 pm, 12 34 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > seqNo = > File.basename(“/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV”,“.\*”)[-1,3].to \_s > seqNo = “-” + seqNo+ “.xx.m” > puts "seqNo: #{seqNo} " # \>\> seqNo: -4.xx.m > > but I want it to be -004.xx.m. In other words I want the leading zeros. Slim2:~ phrogz$ irb irb(main):001:0\> path = “/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV” =\> “/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV” irb(main):002:0\> digits = path[/(\d+).\w+$/, 1] =\> “0004” irb(main):003:0\> my\_seq = “%03d” % digits.to\_i =\> “004” ---
**Author:** ![mtnbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ad7895/32.png) [@mtnbiker](https://www.ruby-forum.com/u/mtnbiker)\ **Post date:** [July 11, 2007, 3:44pm UTC](https://www.ruby-forum.com/t/simple-string-operation/108968/7 "2007-07-11T15:44:51Z")
12 34 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > seqNo = > File.basename(“/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV”,“.\*”)[-1,3].to\_s > seqNo = “-” + seqNo+ “.xx.m” > puts "seqNo: #{seqNo} " # \>\> seqNo: -4.xx.m > > but I want it to be -004.xx.m. In other words I want the leading zeros. seqNo = File.basename(“/Volumes/MINOLTA1/DCIM/100MLT16/PICT0004.MOV”,"._") seqNo = “-” + /\d_$/.match(seqNo)[0] + “.xx.m” puts "seqNo: #{seqNo} " But you might need to change that if you don’t want all three leading zeros (your desired answer omits one). m.