Regex Option - no recursive regex

Question

I'm trying to use System.Text.RegularExpressions.Regex class to grab some text from a JSON string. The sting is something like

[{"name":"joe","message":"hello","sent":"datetime"}{"name":"steve","message":"bye","sent":"datetime"}]

I'm attempting to use the Matches() method to grab the "message" values. However, specifying a match as something like message":"*","sent as the pattern would return 3 matches:

hello
bye
hello","sent":"datetime"}{"name":"steve","message":"bye

How do I structure the options or modify my pattern to exclude recursive regex checks? I only want matches

hello
bye

You may want to address why you're using a RegEx instead of one of the numerous tried-and-true JSON libraries and snippets available in C#. — Spencer Ruport
– Spencer Ruport, Commented Oct 12, 2012 at 1:24
I would recommend using JSON.NET, this is not a good application for RegEx. You can download the package through NuGet in Visual Studio or it can be found here; nuget.org/packages?q=Json.NET — evanmcdonnal
– evanmcdonnal, Commented Oct 12, 2012 at 1:27
Is that really the regex you used? I don't see how it would return those matches. Should * have been .*? — Barmar
– Barmar, Commented Oct 12, 2012 at 2:33
I have edited your title. Please see, "Should questions include “tags” in their titles?", where the consensus is "no, they should not". — John Saunders
– John Saunders, Commented Oct 12, 2012 at 3:00

Monroe Thomas · Accepted Answer · 2012-10-12 02:35:50Z

1

The JavaScriptSerializer class (namespace System.Web.Script.Serialization, assembly System.Web.Extensions.dll) is pretty useful for dealing with JSON strings like this.

var json = "[{\"name\":\"joe\",\"message\":\"hello\",\"sent\":\"datetime\"},{\"name\":\"steve\",\"message\":\"bye\",\"sent\":\"datetime\"}]";

var serializer = new JavaScriptSerializer();
var result = serializer.Deserialize<object[]>(json);

// now have an array of objects, each of which happens to be an IDictionary<string, object>
foreach(IDictionary<string, object> map in result)
{
    var messageValue = map["message"].ToString();
    Console.WriteLine("message = {0}", messageValue);
}

answered Oct 12, 2012 at 2:35

Monroe Thomas

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Guvante · Accepted Answer · 2012-10-12 01:27:49Z

1

JSON is better parsed by a JSON tool.

You can try using the non-greedy syntax .*? for example.

answered Oct 12, 2012 at 1:27

Guvante

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3 Comments

Zee Over a year ago

I couldn't figure out how to use the Json.net DeserializeObject method - Here is what I have so far: string[] messages = new string[NumberOfMessages]; for(int i = 0; i < messages.GetUpperBound(0); i++) { messages[i] = JsonConvert.DeserializeObject<string>(; }

Zee Over a year ago

Note sure how to structure the <>() after DeserializeObject for a string... Thanks you everyone for their input!

Guvante Over a year ago

@Zach: I would recommend posting another question if you want to know about how to use a Json tool.

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