c# - Not able to count line number in richtextbox -

here code

private void allocation_matrix_keypress(object sender, keypresseventargs e)     {         if (e.keychar == 13)         {             int total_row_check;             total_row_check = getrow();             textbox1.text = convert.tostring(total_row_check);             if (total_row_check >= convert.toint32(total_processes.text))             {                 messagebox.show("rows cannot exceed total number of processess");             }         }     }      public int getrow()     {         int row = 0;         string[] arlines;         int i;         arlines = allocation_matrix.text.split(new string[] { environment.newline }, stringsplitoptions.none);         (i = 0; < arlines.length; i++)         {             row++;         }         return row;     } 

i want update textbox1 hit enter in richtextbox keyboard...but textbox keeps show firstrow , shows one(1)

how using richtextbox.getlinefromcharindex method? returns, zero-based line number in character index located.