c# - 如何将字符串附加到数组列表中的每个项目

Question

项目应显示，在附加国家代码后用逗号分隔，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();

标签： c#

Answer 1

您可以缩短代码并在添加到 phonearr 时添加“44”（在此处更改为 phoneList）。

 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();