如何循环遍历 VB.Net 数组？

Question

我现在做这样低效的事情：

' Returns a collection of selected choices in a multichoice field
Dim MyField As NS.ChoiceValues = CType(Me.Form.Fields("Field").Value, NS.ChoiceValues)

If MyField.Choices.Item("Value 1") IsNot Nothing Then
    ' Do stuff to database choice Value 1, which has id 100
End If

If MyField.Choices.Item("Value 1") Is Nothing Then
    ' Do other stuff to database choice Value 1, which has id 100
End If

If MyField.Choices.Item("Value 2") IsNot Nothing Then
    ' Do stuff to database choice Value 2, which has id 200
End If

If MyField.Choices.Item("Value 2") Is Nothing Then
    ' Do other stuff to database choice Value 2, which has id 200
End If

...

This is very inefficient and becomes unreadable when the number of choice values increase. 所以我想更新这个：

Dim Field1Choices As New Dictionary(Of Integer, String) From { 
    {100, "Value 1"}, 
    {200, "Value 2"},
    {300, "Value 3"},
    {400, "Value 4"}
    ...
}

For Each FieldChoice As String In Field1Choices
    If MyField.Choices.Item(var_a) ' var_a should be "Value 1", "Value 2", etc.
        DoStuff.WithCoice(Me.Database, "SomeTable", var_b) 'var_b should be 100, 200 etc. 
    End If
Next

显然，这行不通。 因为我的数组同时包含整数和字符串，所以For Each FieldChoice As String In Field1Choices不起作用。

如何遍历 Field1Choices 数组，以便var_a和var_b获取数组值的值？

Answer 1

Dictionary 中的每个条目都作为KeyValuePair类型返回，该类型具有属性Value和属性Key 。
在 For Each 循环中，您不需要声明迭代器的类型。 编译器通过查看枚举的类型来正确识别它。 在这种情况下，您的 Dictionary 有一个 Integer 键和一个字符串值。 因此，您的KeyValuePair迭代器包含一个 Integer 类型的 Key 和一个 string 类型的值，用于字典中的每个条目

Dim Field1Choices As New Dictionary(Of Integer, String) From { 
    {100, "Value 1"}, 
    {200, "Value 2"},
    {300, "Value 3"},
    {400, "Value 4"}
}

For Each FieldChoice In Field1Choices
    Dim var_A = FieldChoice.Value
    Console.WriteLine(var_A)

    DIm var_B = FieldChoice.Key
    Console.WriteLine(var_B)

    'DoStuff.WithCoice(Me.Database, "SomeTable", var_B) 'var_b should be 100, 200 etc. 

Next