如何將字符串追加到數組列表中的每個項目

Question

項目應顯示，並在附加國家/地區代碼后以逗號分隔，例如44904223322,44504905949,44304940393

 HashSet<string> phonearr = new HashSet<string>();
 conn.Open();
 MySqlCommand sda = new MySqlCommand("select * from members where Branch='" + lbladminbranch.Text + "' and Country='" + lbladmincountry.Text + "'", conn);

 MySqlDataReader dr = sda.ExecuteReader();

 while (dr.Read())
 {
   StringBuilder countrycode = new StringBuilder("44");
   phonearr.Add(dr["Phone"].ToString());

   foreach(string phone in phonearr)
   {
    countrycode.Append(phone);
   }

   txtsmsphoneno.Text = string.Join(",",countrycode );
  }
   conn.Close();

Answer 1

您可以縮短代碼，並在添加到音機時（在此更改為phoneList）添加“ 44”。

 List<string> phoneList = new List<string>();
 conn.Open();
 MySqlCommand sda = new MySqlCommand("select * from members where Branch='" + lbladminbranch.Text + "' and Country='" + lbladmincountry.Text + "'", conn);

 MySqlDataReader dr = sda.ExecuteReader();

 while (dr.Read())
 {
    phoneList.Add("44" + dr["Phone"].ToString());
 }
 txtsmsphoneno.Text = string.Join(",",phoneList);
 conn.Close();