c# - Compare Two Liste <T> -

how can compare 2 list ?

public class pers_ordre : iequalitycomparer<pers_ordre> {     int _ordreid;     public int lettrevoidid     {         { return _lettrevoidid; }         set { _lettrevoidid = value; }     }      string _ordrecummul;     public string ordrecummul     {         { return _ordrecummul; }         set { _ordrecummul = value; }     }      // products equal if names , product numbers equal.      public bool equals(pers_ordre x, pers_ordre y)     {          //check whether compared objects reference same data.          if (object.referenceequals(x, y)) return true;          //check whether of compared objects null.          if (object.referenceequals(x, null) || object.referenceequals(y, null))             return false;          //check whether products' properties equal.          return x.lettrevoidid == y.lettrevoidid && x.ordrecummul == y.ordrecummul;     }      // if equals() returns true pair of objects       // gethashcode() must return same value these objects.       public int gethashcode(pers_ordre product)     {         //check whether object null          if (object.referenceequals(product, null)) return 0;          //get hash code name field if not null.          int hashproductname = product.ordrecummul == null ? 0 : product.ordrecummul.gethashcode();          //get hash code code field.          int hashproductcode = product.lettrevoidid.gethashcode();          //calculate hash code product.          return hashproductname ^ hashproductcode;     } } 

and compare this:

private void simplebutton_comparer_click(object sender, eventargs e) {     string lefile_client = system.io.path.combine(appdir, @"fa.csv");     string lefile_server = system.io.path.combine(appdir, @"fa_server.csv");      list<pers_ordre> olistclient = outils.getcsv(lefile_client).orderby(t => t.lettrevoidid).tolist();     list<pers_ordre> olistservert = outils.getcsvserver(lefile_server).orderby(t => t.lettrevoidid).tolist();       list<pers_ordre> lediff = new list<pers_ordre>();      lediff = olistservert.except(olistclient).tolist();      string noid = "", odreid = "";      foreach (var odiff in lediff)     {         noid += odiff.lettrevoidid + " ";         odreid += odiff.ordrecummul + " ";     }      messagebox.show(noid + "--" + odreid); } 

i can not right result.

the lists contain class objects , iterate through 1 list, looking same item in second list , report differences.

to object contains in list not in list b , vice versa.

your current .except() call find items server missing on client, not find items on client missing on server.

try this:

private void simplebutton_comparer_click(object sender, eventargs e) {     string lefile_client = system.io.path.combine(appdir, @"fa.csv");     string lefile_server = system.io.path.combine(appdir, @"fa_server.csv");      var listclient = outils.getcsv(lefile_client).orderby(t => t.lettrevoidid);     var listserver = outils.getcsvserver(lefile_server).orderby(t => t.lettrevoidid);      var lediff = listserver.except(listclient).concat(listclient.except(listserver));      var result = new stringbuilder();     foreach (var diff in lediff)     {         result.appendformat("{0} --{1} ", diff.lettrevoidid, diff.ordrecummul);     }     messagebox.show(noid.tostring() + "--" + odreid); } 

this code should faster original, avoids loading results memory until builds final string. code in performs equivalent of 2 separate sql left joins. make faster still doing 1 full join, require writing our own linq operator method well.