c# - Adding Data to existing DataTable's DataRow -

i want add data existing datarow in datatable. idea is, without copying data exists.

when writing tests, found out directly inserting data slower copying both existing data , new new row , add row.

or doing wrong?

first create datatable initial data.

fill initial data:

datatable table1 = new datatable(); int count = 15; (int = 0; < count; i++) {     table1.columns.add("hallo" + i, % 2 == 0 ? typeof(int) : typeof(string)); } int newstartindex = table1.columns.count; datetime pre = datetime.now; (int = 0; < 100000; i++) {     datarow row = table1.newrow();     (int j = 0; j < table1.columns.count; j++)     {         if (j % 2 == 0)         {             row[j] = 502;         }         else         {             row[j] = "test";         }     }     table1.rows.add(row); } 

afterwards add 15 columns , data.

for (int = count; < 2 * count; i++) {     table1.columns.add("hallo" + i, % 2 == 0 ? typeof(int) : typeof(string)); }  foreach( datarow row in table1.rows) {     (int j = newstartindex; j < table1.columns.count; j++)     {         if (j % 2 == 0)         {             row[j] = 502;         }         else         {             row[j] = "test";         }     }                } 

when taking time, shows inserting data (which should same data data added) takes 10 times long initial filling.

now tried same copying data:

list<object[]> toadd = new list<object[]>();  foreach (datarow row in table1.rows) {     object[] newarray = new object[table1.columns.count];     array.copy(row.itemarray, newarray, count);                  (int j = newstartindex; j < table1.columns.count; j++)     {         if (j % 2 == 0)         {             newarray[j] = 502;         }         else         {             newarray[j] = "test";         }     }     toadd.add(newarray); } table1.rows.clear(); foreach( var o in toadd) {     table1.rows.add(o); } 

this takes 2.5 times long initial filling, makes lot faster directly inserting.

somehow think there must faster way add data copy , add anew.

i tried writing datarow.itemarray, changes not present in datatable after writing there.

any ideas? , maybe explanations behavior?

i'm not sure why going through such efforts, , have own reasons.
not exact syntax, however, have looked things like...

datatable.clone()  // make copy  datatable.merge()  // merge 1 datatable rows (w/matching columns)  dataview odv = yourdatatable.defaultview odv.filter = ... datatable newtable = odv.totable()