C#成员变量范围

我的VSTO插件中有三/四个函数和一些成员变量：

public void generateClientDict()
{
        clientDict.Add("alcatel-lucent.com", "Alcatel-Lucent");
        clientDict.Add("emerson.com", "Emerson");
        clientDict.Add("ericsson.com", "Ericsson");
        clientDict.Add("fortress-technologies.com", "Fortress Technologies");
        clientDict.Add("genesys.com", "Genesys");
        clientDict.Add("hitachi.com", "Hitachi Data Systems");
        clientDict.Add("hp.com", "Hewlett Packard");
        clientDict.Add("lg.com", "LG Electronics"); 
        clientDict.Add("samsung.com", "Samsung");
        clientDict.Add("sap.com", "SAP");
        clientDict.Add("tellabs.com", "Tellabs");
        clientDict.Add("thiel-audio.com", "Thiel Audio");
        clientDict.Add("xerox.com", "Xerox");
        clientDict.Add("zebra.com", "Zebra Technologies");

        clientHistoryDict.Add("3com.com", "3Com- CommWorks");
        clientHistoryDict.Add("3m.com", "3M");
        clientHistoryDict.Add("abis.com", "ABIS");
        clientHistoryDict.Add("acxiom.com", "Acxiom");
        clientHistoryDict.Add("ajusa.com", "AJ-USA");
        clientHistoryDict.Add("akamai.com", "Akamai Technologies");
        clientHistoryDict.Add("alcatel-lucent.com", "Alcatel-Lucent");
        clientHistoryDict.Add("avaya.com", "Avaya");
        clientHistoryDict.Add("beckmancoulter.com", "Beckman Coulter");
        clientHistoryDict.Add("bellsouth.com", "BellSouth");
        clientHistoryDict.Add("bridgevine.com", "Bridgevine");
        clientHistoryDict.Add("casio.com", "Casio");
        clientHistoryDict.Add("cca.com", "CCA");
        clientHistoryDict.Add("ccs.com", "CCS");
        clientHistoryDict.Add("centurylink.com", "CenturyLink");
        clientHistoryDict.Add("chinatelecom.com", "China Telecom");
        clientHistoryDict.Add("cisco.com", "Cisco");
        clientHistoryDict.Add("comcast.com", "Comcast");
        clientHistoryDict.Add("comodo.com", "Comodo");
        clientHistoryDict.Add("comverge.com", "Comverge");
        clientHistoryDict.Add("coriant.com", "Coriant (Spin off from Tellabs)");
        clientHistoryDict.Add("daneelectric.com", "Dane Electric");
        clientHistoryDict.Add("dell.com", "Dell");
        clientHistoryDict.Add("disney.com", "Disney");
        clientHistoryDict.Add("siemens.com", "Efficient Networks- Siemens");
        clientHistoryDict.Add("emc.com", "EMC");
        clientHistoryDict.Add("emergentcommunications.com", "Emergent Communications");
        clientHistoryDict.Add("emerson.com", "Emerson");
        clientHistoryDict.Add("epson.com", "Epson");
        clientHistoryDict.Add("ericsson.com", "Ericsson");
        clientHistoryDict.Add("exigen.com", "Exigen Services");
        clientHistoryDict.Add("frbny.com", "Federal Reverse Bank of New York");
        clientHistoryDict.Add("hometeamsports.com", "Fox Home Team Sports");
        clientHistoryDict.Add("freemansoundlabs.com", "Freeman Sound Labs");
        clientHistoryDict.Add("genesys.com", "Genesys");
        clientHistoryDict.Add("here.com", "HERE, a Nokia Company");
        clientHistoryDict.Add("hp.com", "Hewlett Packard");
        clientHistoryDict.Add("hitachi.com", "Hitachi Data Systems");
        clientHistoryDict.Add("intel.com", "Intel");
        clientHistoryDict.Add("lg.com", "LG Electronics");
        clientHistoryDict.Add("samsung.com", "Samsung");
        clientHistoryDict.Add("sap.com", "SAP");
        clientHistoryDict.Add("subway.com", "Subway");
        clientHistoryDict.Add("tellabs.com", "Tellabs");
        clientHistoryDict.Add("thiel-audio.com", "Thiel Audio");
        clientHistoryDict.Add("xerox.com", "Xerox");
        clientHistoryDict.Add("zebra.com", "Zebra Technologies");
}

成员变量：

private Dictionary<string, string> clientDict;
private Dictionary<string, string> clientHistoryDict;

现在，此函数可用于成员变量。（所有这些都属于同一类）。但这些功能并不：

public void populateClientDict(SqlConnection conn)
{
        //Dictionary<string, string> clientDict = new Dictionary<string, string>();  If I don't add this I get an error
        try
        {
            using (conn)
            {
                SqlCommand command = new SqlCommand(
                  @"SELECT ClientDirName, ClientEmailDomain FROM ClientTable;",
                  conn);
                conn.Open();

                SqlDataReader reader = command.ExecuteReader();

                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        string clientDir = reader.GetString(0);
                        string clientEmail = reader.GetString(1);
                        clientDict.Add(clientEmail, clientDir);
                    }
                }
                else
                {
                    MessageBox.Show("No rows found in ClientTable", "Rows Not Found", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                reader.Close();
            }
        }
        catch (InvalidOperationException ex)
        {
            MessageBox.Show(String.Format("Exception while accessing ClientTable: {0}", ex), "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        catch (SqlException ex)
        {
            MessageBox.Show(String.Format("Exception while accessing ClientTable: {0}", ex), "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
}

public void populateClientHistoryDict(SqlConnection conn)
{
        //Dictionary<string, string> clientHistoryDict = new Dictionary<string, string>(); if I don't add this I get an error
        try
        {
            using (conn)
            {
                SqlCommand command = new SqlCommand(
                  @"SELECT ClientDirName, ClientEmailDomain FROM ClientHistoryTable;",
                  conn);
                conn.Open();

                SqlDataReader reader = command.ExecuteReader();

                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        string clientDir = reader.GetString(0);
                        string clientEmail = reader.GetString(1);
                        clientHistoryDict.Add(clientEmail, clientDir);
                    }
                }
                else
                {
                    MessageBox.Show("No rows found in ClientHistoryTable", "Rows Not Found", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                reader.Close();
            }
        }
        catch (InvalidOperationException ex)
        {
            MessageBox.Show(String.Format("Exception while accessing ClientHistoryTable: {0}", ex), "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        catch (SqlException ex)
        {
            MessageBox.Show(String.Format("Exception while accessing ClientHistoryTable: {0}", ex), "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
}

我感觉这个错误与函数的这一部分有关，它说：

while (reader.Read())
{
clientDir = reader.GetString(0);
string clientEmail = reader.GetString(1);
clientDict.Add(clientEmail, clientDir);
}

ID是第一列，clientDir是第二列，clientmail是第三列。可能我使用的

reader.GetString（）

不正确？我在某个地方读到过类似于

reader.GetString[“ClientDirName”]

（ClientDirName是列名）的内容，但我不确定该做什么

这可能是导致错误的原因吗？如果是这样，如何正确访问第2列和第3列（提供的ID是第一列）以避免此错误

如果不是的话，还有什么可能导致它

我已经尝试了大量的组合，正如我所说的，如果我在函数中移动字典实例化，它会起作用，但我认为这并不能解决实际问题

---

非常感谢您提供的任何帮助。

我猜您忘了像在

函数中那样实例化
clientDict
成员
变量

由于您在
函数中声明了相同的变量并进行了实例化，因此它采用了本地范围（在不使用
this
的情况下使用），并且有效

您可以在
构造函数中或在
声明过程中实例化私有成员

private Dictionary<string, string> clientDict=new Dictionary<string, string>();
private Dictionary<string, string> clientHistoryDict=new Dictionary<string, string>();

private Dictionary clientDict=new Dictionary（）；
专用词典clientHistoryDict=新词典（）；

如果您想了解更多有关作用域的信息，请点击链接。
我猜您忘记了在
构造函数中实例化您的私有
clientDict
成员
变量
。最好在
构造函数中实例化它们。如果调用正在实例化成员的
函数
“first”，或者只需执行private Dictionary clientDict=new Dictionary（），则可能会起作用；如果您想了解有关作用域的更多信息，请点击此链接否，在
函数
中声明的变量在其他
函数
中不可访问。它仅在包含函数的
local
范围内。
private Dictionary<string, string> clientDict=new Dictionary<string, string>();
private Dictionary<string, string> clientHistoryDict=new Dictionary<string, string>();