# Help parsing and extracting a num **URL:** \ **Category:** Ruby\ **Created:** [March 25, 2008, 3:39pm UTC](https://www.ruby-forum.com/t/help-parsing-and-extracting-a-num/132883 "2008-03-25T15:39:29Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [March 25, 2008, 3:39pm UTC](https://www.ruby-forum.com/t/help-parsing-and-extracting-a-num/132883/1 "2008-03-25T15:39:29Z")
Hi, I’m trying to extract a num from a string. This string is in fact some number of headers separated by \r\n or \n. for now I just need to extract the value of “Content-Length” (case insensitive) header. For example: irb\> headers = “Via: via1,via2,\r\n via3\r\nFrom: from\_user@domain\nContent-length: 22\r\nTo: to\_user@domain\n” I do the following: irb\> headers.scan(/content-length\s\*:\s\*([0-9]\*)/i).to\_s.to\_i =\> 22 In case the “Content-Length” header exist but has empty value I get 0 with the above code (that’s what I need in fact). Is there any way faster to do the same? any help? Thanks a lot. ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [March 25, 2008, 3:51pm UTC](https://www.ruby-forum.com/t/help-parsing-and-extracting-a-num/132883/2 "2008-03-25T15:51:24Z")
2008/3/25, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > Hi, I’m trying to extract a num from a string. This string is in fact > some number of headers separated by \r\n or \n. for now I just need to > extract the value of “Content-Length” (case insensitive) header. Why don’t you use Net::Http? IIRC this gives you individual header fields already. > In case the “Content-Length” header exist but has empty value I get 0 > with the above code (that’s what I need in fact). > > Is there any way faster to do the same? any help? headers[/content-length:\s\*(\d+)/i, 1].to\_i Cheers robert ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [March 25, 2008, 4:03pm UTC](https://www.ruby-forum.com/t/help-parsing-and-extracting-a-num/132883/3 "2008-03-25T16:03:22Z")
2008/3/25, Robert K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > 2008/3/25, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > > > Hi, I’m trying to extract a num from a string. This string is in fact > > some number of headers separated by \r\n or \n. for now I just need to > > extract the value of “Content-Length” (case insensitive) header. > > Why don’t you use Net::Http? IIRC this gives you individual header > fields already. Yes, but I’m doing a parser for SIP protocol (similar to HTTP but not the same). > headers[/content-length:\s\*(\d+)/i, 1].to\_i Great ! Thanks. ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [March 25, 2008, 5:35pm UTC](https://www.ruby-forum.com/t/help-parsing-and-extracting-a-num/132883/4 "2008-03-25T17:35:13Z")
2008/3/25, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > "Via: via1,via2,\r\n via3\r\nFrom: from\_user@domain\nContent-length: > > \r\n1234: blabla\nTo: to\_user@domain\n"[/content-length\s\*:\s\*(\d+)/i, > 1].to\_i > =\> 1234 > > I’m trying to solve it by ading [^(\r|\n)] after (\d+) but I get > nothing. Please, could you help me with this? I think I have now the solution. The problem is that \s matches also \n so what I do now is: [/content-length\s\*:[\t]\*(\d+)/i, 1].to\_i (I allow any space or tab before the expected numbers but no \r or \n). ---
**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\ **Post date:** [March 25, 2008, 5:29pm UTC](https://www.ruby-forum.com/t/help-parsing-and-extracting-a-num/132883/5 "2008-03-25T17:29:40Z")
> 2008/3/25, Robert K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > > headers[/content-length:\s\*(\d+)/i, 1].to\_i There is a small issue here that I can’t solve. Imagine there is “Content-Length” header bt with empty value, and the next header has a numeric header name: * * * ## Content-Length: 1234: blablabla In that case the code above returns 1234 while it should return 0. Demostration: “Via: via1,via2,\r\n via3\r\nFrom: from\_user@domain\nContent-length: \r\n1234: blabla\nTo: to\_user@domain\n”[/content-length\s\*:\s\*(\d+)/i, 1].to\_i =\> 1234 I’m trying to solve it by ading [^(\r|\n)] after (\d+) but I get nothing. Please, could you help me with this? Thanks a lot in advance and best regards.