C#字符串处理

C#字符串处理、字符串转数组、数组转字符串


一、指示指定的String对象是空引用还是Empty字符串。（如果value参数为空引用或空字符串 ("")，则为true；否则为 false。）
  if (!string.IsNullOrEmpty("字符串"))
  {}


二、定义字符串
  string str= string.Empty;


三、IDataReader中读取数据空字符串处理
  if (reader["MessageHistoryID"] == DBNull.Value)
  {
      model.IsRead = true;
  }


  if(ds.Tables[0].Rows[0]["ID"].ToString()!="")
  {
      model.ID=int.Parse(ds.Tables[0].Rows[0]["ID"].ToString());
  }


四、List<int>集合转换为字符串
  List<int> list = new List<int>();
  list.Add(100);
  list.Add(90);
  list.Add(60);
  list.Add(80);
  list.Add(10);
  list.Add(40);
  list.Add(20);
  list.Add(10);
  list.Add(50);
  list.Add(50);


  ///所见即所得
  string strArr = string.Join(",", list.ToArray());
  ///升序
  string strArrOrderBy = string.Join(",", list.ToArray().OrderBy(o => o));
  ///降序
  string strArrOrderByDesc = string.Join(",", list.ToArray().OrderByDescending(o => o));
  ///去除重复
  string strArrDistinct = string.Join(",", list.ToArray().Distinct());
  ///排序、去除重复
  string strArrOrderByDescDistinct = string.Join(",", list.ToArray().OrderByDescending(o => o).Distinct());


  strArr输出结果：100,90,60,80,10,40,20,10,50,50
  strArrOrderBy输出结果：10,10,20,40,50,50,60,80,90,100
  strArrOrderByDesc输出结果：100,90,80,60,50,50,40,20,10,10
  strArrDistinct输出结果：100,90,60,80,10,40,20,50
  strArrOrderByDescDistinct输出结果：100,90,80,60,50,40,20,10


五、字符串转数组
  #region 字符串转数组
  List<int> listArr = new List<int>();
  string str = "gfedfdasfdasferwq431241324321ablk";
  var query = from s in str orderby s select s;
  char[] sortStr = query.ToArray();
  string strRes = new string(sortStr);
  Label1.Text = strRes;
  #endregion


  #region 字符串转数组
  List<int> listStrArr = new List<int>();
  string strapp = "19,92,63,45,51,62,47,85,9,10";
  string[] strtemp = strapp.Split(',');
  foreach (string item in strtemp)
  {
      listStrArr.Add(Convert.ToInt32(item));
  }
  Label1.Text = string.Join(",", listStrArr.ToArray());
  
  var num = "1,2,3,4,5,6".Split(',').Select(v => Convert.ToInt32(v)).ToArray();
  string aa = num[0].ToString();
  string bb = num[1].ToString();


  #endregion


六、List<T>.Contains方法（确定某元素是否在 List<T> 中）
  List<int> idList = new List<int>();
  while (reader.Read())
  {
      Message model = Message(reader);
      if (!idList.Contains(model.MessageID))
          idList.Add(model.MessageID);
      list.Add(model);
  }


七、过滤特殊字符
   public string DelQuota(string str)
   {
       string result = str;
       string[] strQuota = { "~", "!", "@", "#", "$", "%", "^", "&", "*", "(", ")", "`", ";", "'", ",", ".", "/", ":", "/,", "<", ">", "?" };
       for (int i = 0; i < strQuota.Length; i++)
       {
           if (result.IndexOf(strQuota[i]) > -1)
               result = result.Replace(strQuota[i], "");
       }
       return result;
   }