System.Collections.Generic.List <string>'不包含'add'的定义

Question

我使用以下代码

public HttpResponseMessage Getdetails([FromUri] string[] Column)
    {
      List<string> selectionStrings;
      var colDict = new Dictionary<string, string>()
            {
            {"CATEGORY", "STCD_PRIO_CATEGORY_DESCR.DESCR"},
            {"SESSION_NUMBER", "STRS_SESSION3.SESSION_NUM"},
            {"SESSION_START_DATE","Trunc(STRS_SESSION3.START_DATE)"}
            };
      foreach (string col in Column)
      {
        string selector = colDict[col];
        selectionStrings.add(string.Format("{0} AS {1}", selector, col));
      }
      var strQuery = string.Format(@"SELECT {0}
                                     from STCD_PRIO_CATEGORY");
  }

但是得到了错误

selectionStrings.add(string.Format("{0} AS {1}", selector, col));

话

'System.Collections.Generic.List'不包含'add'的定义,也没有扩展方法'add'接受类型'System.Collections.Generic.List'的第一个参数(你是否缺少using指令或装配参考？)

我尝试添加,using System.Collections.Generic.List但它不起作用

Answer 1

尝试使用Add而不是add,

selectionStrings.Add(string.Format("{0} AS {1}", selector, col));

还初始化selectionStrings,目前你的代码会抛出异常

List<string> selectionStrings = new List<string>();