[c#] Convert object to JSON string in C#

Possible Duplicate:
Turn C# object into a JSON string in .NET 4

In the Java, I have a code to convert java object to JSON string. How to do the similar in the C# ? which JSON library I should use ?

Thanks.

JAVA code

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class ReturnData {
    int total;

    List<ExceptionReport> exceptionReportList;  

    public String getJSon(){
        JSONObject json = new JSONObject(); 

        json.put("totalCount", total);

        JSONArray jsonArray = new JSONArray();
        for(ExceptionReport report : exceptionReportList){
            JSONObject jsonTmp = new JSONObject();
            jsonTmp.put("reportId", report.getReportId());      
            jsonTmp.put("message", report.getMessage());            
            jsonArray.add(jsonTmp);         
        }

        json.put("reports", jsonArray);
        return json.toString();
    }
    ...
}

Use .net inbuilt class JavaScriptSerializer

  JavaScriptSerializer js = new JavaScriptSerializer();
  string json = js.Serialize(obj);