如何从函数返回字符串数组？

Question

我试图从一个查询中获取三个字符串值，但是这个函数调用：

argVals = GetArgValsForCompanyName(coName)

...使用错误消息编译失败，“'String' 类型的值无法转换为'String 的一维数组'。”

该函数末尾的这一行也不编译：

Return args

...失败，“'一维字符串数组'类型的值不能转换为'字符串'。”

我像这样声明 argVals，作为三个 val 的字符串数组：

Dim argVals(2) As String

...和这样的功能：

Protected Function GetArgValsForCompanyName(coName As String) As String

有关更多上下文，这里是（我认为）完整的相关代码：

Private Sub Button1_Click( sender As Object,  e As EventArgs) Handles Button1.Click
    Dim connStr As String = "SERVER=PLATYPUS42;DATABASE=duckbilldata;UID=vonnegut;PWD=ryecatcher"
    Dim upd8DML As String = "UPDATE CustomerCategoryLog SET Category = 'Exploding' WHERE Unit = @Unit And MemberNo = @MemberNo AND Custno = @CustNo"
    Dim coName As String
    Dim argVals(2) As String
    Dim _Unit As String
    Dim _MemberNo As String
    Dim _CustNo As String
    Dim curIndexVal As String

    For Each cntrl As Control In Me.Controls
        If TypeOf cntrl Is CheckBox Then
            If DirectCast(cntrl, CheckBox).Checked = True Then
                curIndexVal = CStr(DirectCast(cntrl, CheckBox).Tag)
                coName = GetLabelTextForID(curIndexVal)
                argVals = GetArgValsForCompanyName(coName)
                _Unit = argVals(0)
                _MemberNo = argVals(1)
                _CustNo = argVals(2)
                Using conn As New SqlConnection(connStr), _
                    cmd As New SqlCommand(upd8DML, conn)
                    cmd.Parameters.Add("@Unit", SqlDbType.VarChar, 50).Value = _Unit
                    cmd.Parameters.Add("@MemberNo", SqlDbType.VarChar, 50).Value = _MemberNo
                    cmd.Parameters.Add("@CustNo", SqlDbType.VarChar, 50).Value = _CustNo
                    conn.Open
                    cmd.ExecuteScalar()
                End Using
            End If
        End If
    Next
End Sub

Protected Function GetArgValsForCompanyName(coName As String) As String
    Dim args(2) As String
    Dim sqlConnection1 As New SqlConnection("SERVER=PLATYPUS42;DATABASE=duckbilldata;UID=salinger;PWD=dresdenoflions")
    Dim cmd As New SqlCommand
    Dim reader As SqlDataReader

    cmd.CommandText = "select Unit, MemberNo, CustNo from Customers WHERE CompanyName = @CoName"
    cmd.CommandType = CommandType.Text
    cmd.Parameters.Add("@CoName", SqlDbType.VarChar, 50).Value = coName
    cmd.Connection = sqlConnection1
    sqlConnection1.Open()

    sqlConnection1.Open()

    reader = cmd.ExecuteReader()
    If reader.HasRows Then
            args(0) = reader.Item(0).ToString()
            args(1) = reader.Item(1).ToString()
            args(2) = reader.Item(2).ToString()
    End If
    reader.Close()
    sqlConnection1.Close()

    Return args
End Function

我在这里做错了什么？如何从函数中传回一个字符串数组，然后将这些 val 存储在三个 var (dims) 中？

注意：如果我尝试像这样声明函数：

Protected Function GetArgValsForCompanyName(coName As String) As String(2)

...我明白了，“数组边界不能出现在类型说明符中”

Answer 1

你的问题似乎是你有这样的功能签名

Protected Function GetArgValsForCompanyName(coName As String) As String

什么时候应该是这样的

Protected Function GetArgValsForCompanyName(coName As String) As String()

返回类型末尾的 () 表明它将是一个字符串数组，而不仅仅是一个字符串。