# Regular expressions - string substitution **URL:** \ **Category:** Ruby\ **Created:** [September 4, 2009, 4:21pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955 "2009-09-04T16:21:59Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:21pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/1 "2009-09-04T16:21:59Z")
Hello all, A quick question if I have a string like so 000000100 and I want to remove the leading 0’s to leave me with a string like so 100 What is the best way to do this? initially I was using string.delete(“0”) but that obviously deletes every 0 and is not the desired outcome. I then though string.gsub(/^0/, “”) however this only gets rid of the very first 0. Does anyone have any suggestions? Thanks a lot ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:28pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/2 "2009-09-04T16:28:20Z")
“000000100”.to\_i.to\_s # =\> 100 ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:29pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/3 "2009-09-04T16:29:37Z")
So long as you’ll always be converting numbers, you can use to\_i. That will convert the string into an integer. > “000000100”.to\_i > =\> 100 Keep in mind that it will truncate the number as soon as it reaches a non-number. For instance: > “00012,345,678”.to\_i > =\> 12 If you need to keep decimals then you can use to\_f. For example: > “0001234.567”.to\_f > =\> 1234.567 ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:38pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/4 "2009-09-04T16:38:48Z")
Thanks all. I completely forgot about that. It always the simple things Marc H. wrote: > “000000100”.to\_i.to\_s # =\> 100 ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:43pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/5 "2009-09-04T16:43:16Z")
On Fri, 4 Sep 2009 23:24:34 +0900 Ne Scripter [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > string.gsub(/^0/, “”) Try something like this: string.gsub(/^0\*/, “”) This means: 0 or more occurrences of character “0”, starting at the beginning of the string. ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:42pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/6 "2009-09-04T16:42:45Z")
Ne Scripter wrote: > Thanks all. I completely forgot about that. It always the simple things > > Marc H. wrote: > > > “000000100”.to\_i.to\_s # =\> 100 > > > I then though string.gsub(/^0/, “”) however this only > > > gets rid of the very first 0. string.gsub(/^0+/,"") ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:45pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/7 "2009-09-04T16:45:02Z")
On Sep 4, 2009, at 9:24 AM, Ne Scripter wrote: > What is the best way to do this? initially I was using > string.delete(“0”) but that obviously deletes every 0 and is not the > desired outcome. I then though string.gsub(/^0/, “”) however this only > gets rid of the very first 0. Does anyone have any suggestions? “000000100”.sub(/\A0+/, “”) \A means the beginning of the String and 0+ means one or more zeros. Also note the use of sub() which only matches once over gsub() which is used to repeat for all matches. There can only be one run of zeros at the front of the String, so sub() is all we need. Hope that helps. James Edward G. II ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:47pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/8 "2009-09-04T16:47:58Z")
Hello, > What is the best way to do this? initially I was using > string.delete(“0”) but that obviously deletes every 0 and is not the > desired outcome. I then though string.gsub(/^0/, “”) however this only > gets rid of the very first 0. Does anyone have any suggestions? string.sub(/^0+/,’’) should do what you are looking for. Cheers, ---
**Author:** ![nescripter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/2acd7d/32.png) [@nescripter](https://www.ruby-forum.com/u/nescripter)\ **Post date:** [September 4, 2009, 4:53pm UTC](https://www.ruby-forum.com/t/regular-expressions-string-substitution/174955/9 "2009-09-04T16:53:14Z")
On Sep 4, 2009, at 10:24 AM, Ne Scripter wrote: > What is the best way to do this? initially I was using > string.delete(“0”) but that obviously deletes every 0 and is not the > desired outcome. I then though string.gsub(/^0/, “”) however this only > gets rid of the very first 0. Does anyone have any suggestions? > > ## Thanks a lot string.sub(/^0\*/,‘’) Or /^0+/ since both work if there are zeroes, but find nothing if the first character is not a 0. If your intention is to convert to a number, then one of the other responses will work, but since you presented a string and asked to be left with a string, I wanted to be sure you saw this simple tweak to what you’d already discovered. -Rob Rob B. [http://agileconsultingllc.com](http://agileconsultingllc.com) removed\_email\_address@domain.invalid