What is the best way to parse this string in C#?

Question

I have a string that I am reading from another system. It's basically a long string that represents a list of key value pairs that are separated by a space in between. It looks like this:

 key:value[space]key:value[space]key:value[space] 

So I wrote this code to parse it:

string myString = ReadinString(); string[] tokens = myString.split(' '); foreach (string token in tokens) {      string key = token.split(':')[0];      string value = token.split(':')[1];      .  . . .  } 

The issue now is that some of the values have spaces in them so my "simplistic" split at the top no longer works. I wanted to see how I could still parse out the list of key value pairs (given space as a separator character) now that I know there also could be spaces in the value field as split doesn't seem like it's going to be able to work anymore.

NOTE: I now confirmed that KEYs will NOT have spaces in them so I only have to worry about the values. Apologies for the confusion.

Answer 1

Use this regular expression:

\w+:[\w\s]+(?![\w+:]) 

I tested it on

test:testvalue test2:test value test3:testvalue3 

It returns three matches:

test:testvalue test2:test value test3:testvalue3 

You can change \w to any character set that can occur in your input.

Code for testing this:

var regex = new Regex(@"\w+:[\w\s]+(?![\w+:])"); var test = "test:testvalue test2:test value test3:testvalue3";  foreach (Match match in regex.Matches(test)) {     var key = match.Value.Split(':')[0];     var value = match.Value.Split(':')[1];      Console.WriteLine("{0}:{1}", key, value); } Console.ReadLine(); 

As Wonko the Sane pointed out, this regular expression will fail on values with :. If you predict such situation, use \w+:[\w: ]+?(?![\w+:]) as the regular expression. This will still fail when a colon in value is preceded by space though... I'll think about solution to this.

Answer 2

This cannot work without changing your split from a space to something else such as a "|".

Consider this:

Alfred Bester:Alfred Bester Alfred:Alfred Bester

• Is this Key "Alfred Bester" & value Alfred" or Key "Alfred" & value "Bester Alfred"?