# How to include a string into a regex comparison? **URL:** \ **Category:** Ruby\ **Created:** [July 31, 2009, 11:26am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016 "2009-07-31T11:26:50Z")\ **Posts on this page:** 7\ **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:** [July 31, 2009, 11:26am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/1 "2009-07-31T11:26:50Z")
Hi, I don’t get solving the following issue (sure it’s easy but I cannot do it): valid\_content\_type = “application/auth-policy+xml” received\_content\_type = “application/auth-policy+xml;charset=ISO-8859-1” received\_content\_type =~ /^application/auth-policy+xml;?/ =\> 0 received\_content\_type =~ /^#{received\_content\_type};?/ =\> nil How to fix it? 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:** [July 31, 2009, 11:35am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/2 "2009-07-31T11:35:02Z")
2009/7/31 Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > =\> nil > > How to fix it? Thanks a lot. Solved: received\_content\_type =~ /^#{Regex.escape(received\_content\_type)};?/ =\> 0 ---
**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:** [July 31, 2009, 11:45am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/3 "2009-07-31T11:45:34Z")
Le 31 juillet à 11:25, Iñaki Baz C. a écrit : > Hi, I don’t get solving the following issue (sure it’s easy but I cannot do it): > How to fix it? Thanks a lot. > valid\_content\_type = “application/auth-policy+xml” When you insert a string inside a regexp, it’s evaluated as is by the regexp engine. You need to escape the special characters (here, the +), by prepending backslashes or asking the Regexp class to do it for you : > > received\_content\_type =~ /^#{Regexp::escape(received\_content\_type)};?/ > > =\> 0 Or : > > valid\_content\_type = Regexp::escape(“application/auth-policy+xml”) > > =\> “application/auth\-policy\+xml” > > > received\_content\_type =~ /^#{received\_content\_type};?/ > > =\> 0 Fred ---
**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:** [July 31, 2009, 11:46am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/4 "2009-07-31T11:46:44Z")
On Fri, Jul 31, 2009 at 11:25 AM, Iñaki Baz C.[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > valid\_content\_type = “application/auth-policy+xml” > received\_content\_type = “application/auth-policy+xml;charset=ISO-8859-1” > > received\_content\_type =~ /^application/auth-policy+xml;?/ > =\> 0 > > received\_content\_type =~ /^#{received\_content\_type};?/ > =\> nil > > How to fix it? Thanks a lot. Try this: irb(main):001:0\> valid\_content\_type = “application/auth-policy+xml” =\> “application/auth-policy+xml” irb(main):002:0\> received\_content\_type = “application/auth-policy+xml;charset=ISO-8859-1” =\> “application/auth-policy+xml;charset=ISO-8859-1” irb(main):005:0\> re = /^#{Regexp.escape(valid\_content\_type)};?/ =\> /^application/auth-policy+xml;?/ irb(main):006:0\> received\_content\_type =~ re =\> 0 Hope this helps, Jesus. ---
**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:** [July 31, 2009, 11:49am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/5 "2009-07-31T11:49:05Z")
El 31 de julio de 2009 11:45, Jesús Gabriel y Galán[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) escribió: > =\> 0 > Thanks to all, the fact is that I already solved the issue doing > exactly the same 🙂 > I replied to myself in the maillist. Thanks a lot for all your help. ---
**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:** [July 31, 2009, 11:47am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/6 "2009-07-31T11:47:54Z")
On Fri, Jul 31, 2009 at 11:34 AM, Iñaki Baz C.[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > 2009/7/31 Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > Solved: > > received\_content\_type =~ /^#{Regex.escape(received\_content\_type)};?/ > =\> 0 Oh, sorry, I missed you already solved it. Anyway I wanted to point out that maybe what you want in the Regex.escape is valid\_content\_type not received\_content\_type… Jesus. ---
**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:** [July 31, 2009, 11:50am UTC](https://www.ruby-forum.com/t/how-to-include-a-string-into-a-regex-comparison/173016/7 "2009-07-31T11:50:50Z")
El 31 de julio de 2009 11:46, Jesús Gabriel y Galán[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) escribió: > not received\_content\_type… > Oh yes, sure, it was a typo just in the mail, in my code I did it > correctly 🙂 Thanks a lot.