Convert user input to url

Question

I need to search through a string entered by a user and convert anything that is plain text and resembles a url into a url.

Im not concerned with how to construct the URL, more how to determine if the text is actually a url. I was thinking about a regular expression (see How to replace plain URLs with links?), but ideally would like a solution that is more readable.

I suppose I would need to search for instances of http or www and wrap the string up until the next space in an anchor tag.

Does anyone have any pointers, especially seen as urls can be so varied now a days?

EDIT:

A user enters text into an input that is submitted, when displayed on screen I need to check their comment for any possible links and convert them to a hyperlink.

Does this work for you? http://stackoverflow.com/questions/927847/is-there-a-url-validator-on-net — luiscubal, Oct 08 '13 at 10:39
I didn't know about this, thanks! This would mean splitting the text by space and passing every item through this function, and if it returns true then I can wrap it in an anchor. Does this sound plausible? — DavidB, Oct 08 '13 at 10:45
What `anchor` tag? You mean like HTML ``? And why do you need to split the text by space? Do you have multiple URLs? Do you have URLs embedded in text that *isn't* an URL? — luiscubal, Oct 08 '13 at 10:47
See http://stackoverflow.com/questions/285619/how-to-detect-the-presence-of-url-in-a-string It's Java but it might be a valuable starting point. — luiscubal, Oct 08 '13 at 10:53
Given you need to *match* & *extract* specific text from a string, a regex is the best way to go here. The link you provided looks like it does exactly what you are after. In terms of making it more "readable", just place the regex code into a readable function. The example you gave wraps it in a nice "*replaceURLWithHTMLLinks*" method - seems readable enough to me? — James, Oct 08 '13 at 10:54
Thanks, It seems similar to what I was thinking, ie search for www or http to locate a possible link. — DavidB, Oct 08 '13 at 10:55

score 0 · Answer 1 · answered Oct 09 '13 at 15:58

The first thing you need to do is look for anything that validated as an url. At what point do you want a url to be a url.

An valid url produces a result when entered in the browser addressbar produces a (desired) result ;

google.com

www.google.com

http://google.com

http://www.google.com

all of the above produce a result when typed in your browsers address bar. so if your tekst has any string that has no whitespace but has a dot ! its possible that its an url

(?<=[ ]).*?..+?(?=[ ])

will get your google.com out of

does google.com validated as an url

however determining if its a url can only be confirmed when you actually try to get the page.

The regex above will get you all 4 urls above, but also get you foobars. If you want to make sure you have a valid url, do a lookup of the page, if it turns 404 on you, it wasnt an url

thanks, but ive got a good solution that will create a link out anythign starting https, http, ftp, www and will also create mailto links. Yours is a good suggestion but overkill I think for what I want — DavidB, Oct 10 '13 at 08:35

Convert user input to url

1 Answers1