Attribute request with clause IN

Question

Hello Every One i have a problem with a Attribute request with clause IN 
In fact i have an collection of integer and i want use the attribute requeste with IN ,that dosent work 
below is the code ,i use to perform the task:

QueryTask qTask = new QueryTask("URL");
                    qTask.ExecuteCompleted += qTaskRemplirCbox_completed;
                    Query mquery = new Query();
                    mquery.OutFields.Add("*");
                    mquery.Where = "Code_Pref  IN" + listcode; //Code_Pref is the field on the layer  ,and listcode is the collection of  
                                                                               the  integer

qTask.ExecuteAsync(mquery);

private void qTaskRemplirCbox_completed(Object sender, QueryEventArgs e)
          {
            //The graphics from the result Task but empty beacause the task are not executed completed.

}
i want to know if the request (mquery.Where = "Code_Pref  IN" + listcode) are just or if something wrong ?

thanks in advance for any Help .

DIALLOAbdoulaye · Answer

thanks for the help  cc4ever 
that work well .

AhmedEl-Sisi · Answer

Your values should be comma separated and inside Brackets for IN operator
ex: "Code_Pref IN (value1,value2,value3,..)"

It should be something like the following:
 if (listcode.Count>0)
 {
      mquery.Where = "Code_Pref IN (" + string.Join(",", listcode.Select(x => x.ToString()).ToArray()) + ")";
 }

Regards,