Group (SharePoint group, domain group) contain current user

    Private   Bool Addusergrouping group (spweb, String Sgroupname, Int  Iuserid ){  Bool Res = False  ;  Try  {Web. allowunsafeupdates = True  ; Spgroup ogroup = Web. sitegroups [sgroupname]; spuser ouser =Web. allusers. getbyid (iuserid );  If (Ouser! = Null  ) {Ogroup. adduser (ouser); ogroup. Update (); Res = True  ;} Web. Update ();}  Catch  {}  Return  Res ;}  Private   Bool Createsitegroup (spweb rootweb,String Sgroupname, String  Sgroupdescription ){  Bool Res = False  ;  Try  {Rootweb. allowunsafeupdates = True  ; Spgroupcollection collgroups = Rootweb. sitegroups;  String Sloginname =Rootweb. currentuser. loginname; spuser ouser = Rootweb. siteusers [sloginname]; spmember omember = Rootweb. siteusers [sloginname]; collgroups. Add (sgroupname, omember, ouser, sgroupdescription); Res = True  ; Rootweb. Update ();}  Catch  (Exception ex) {response. Write (  "  Error:  " + Ex. Message + " <Br/>  "  );  Return   False  ;}  Return  Res ;}  Private   Void Deletesitegroup (spweb web, String  Groupname ){  Try  {Web. allowunsafeupdates = True ; Spgroupcollection groups = Web. sitegroups; groups. Remove (groupname); web. Update ();}  Catch  {}}  Private   Bool Iscontaincurrentuser ( Object  OBJ ){  Bool Result = False  ;  If (OBJ = Null ){  Return   False  ;} Spsite securitysite = Null  ; Spweb securityweb = Null  ; Spweb tempweb = Null  ;  Try  {Spfielduservaluecollection approverscollection; spweb Web =Spcontext. Current. Web; web. allowunsafeupdates = True  ;  Bool Groupflag = False  ;  String Groupname = "  GRP  " + Guid. newguid (). tostring ();  //  Response. Write ("groupname:" + groupname + "<br/> "); Spsecurity. runwithelevatedprivileges ( Delegate  (){  Using (Securitysite = New  Spsite (spcontext. Current. Site. ID )){  Using (Securityweb = Securitysite. rootweb) {groupflag = Createsitegroup (securityweb, groupname, ""  );  // Response. Write ("groupflag:" + groupflag. tostring () + "<br/> ");  }}}); Approverscollection = (Spfielduservaluecollection) OBJ;  Int Id = Spcontext. Current. Web. currentuser. ID;  Foreach (Spfielduservalue In  Approverscollection ){  If (Spfielduservalue. User = Null ){  //  Response. Write ("group" + spfielduservalue. lookupvalue + "<br/> ");                      If  (Web. sitegroups [spfielduservalue. lookupvalue]. containscurrentuser) {result = True  ;  Break  ;}}  Else  {  If (Spfielduservalue. lookupid = ID) {result = True  ;  Break  ;}  Else  {Addusermetadata group (securityweb, groupname, spfielduservalue. lookupid );}}}  //  System. Threading. thread. Sleep (500 ); Tempweb = Spcontext. Current. Site. openweb (); If (! Result ){  //  Validate domain user has current user                  If  (Groupflag ){  //  Response. Write (spcontext. Current. Web. sitegroups [groupname]. Users. Count );  Spgroup Group = Tempweb. sitegroups [groupname];  If (Group. containscurrentuser) {result = True  ;}}}  //  Delete Group  Deletesitegroup (securityweb, groupname );}  Catch  (Exception ex ){  //  Return false; Response. Write ( "  Error: " + Ex. Message );}  Finally  {  If (Securityweb! = Null  ) {Securityweb. Dispose (); securityweb = Null  ;}  If (Securitysite! = Null  ) {Securitysite. Dispose (); securitysite =Null  ;}  If (Tempweb! = Null  ) {Tempweb. Dispose (); tempweb = Null  ;}}  Return  Result ;} 

Usage: bool flag =! Iscontaincurrentuser (sourceitem ["Reader"]);