vba - ReDim Preserve 有什么作用？

Question

我正在看别人的vba excel代码。他们在两个循环中都执行 ReDim Preserve dataMatrix(7, i) 。这是做什么的？

另外，第二个循环似乎只是覆盖了第一个循环中的数据，对吗？

Dim dataMatrix() As String

    Worksheets.Item("ETS").Select
    Do While Trim(Cells(r, 1)) <> ""
       Debug.Print "The line: ", Trim(Cells(r, 1)), r
        r = r + 1
        dataMatrix(1, i) = Trim(Cells(r, 1))    ''file name
        dataMatrix(2, i) = Trim(Cells(r, 2))    ''sample type
        dataMatrix(3, i) = Trim(Cells(r, 3))    ''sample name
        dataMatrix(4, i) = "ETS"    ''
        dataMatrix(5, i) = Trim(Cells(r, 5))    ''Response
        dataMatrix(6, i) = Trim(Cells(r, 6))    ''ISTD Response
        dataMatrix(7, i) = Trim(Cells(r, 10))   ''Calculated Conc
        i = i + 1
        ReDim Preserve dataMatrix(7, i)
    Loop

    r = 5
    Worksheets.Item("ETG").Select
    Do While Trim(Cells(r, 1)) <> ""
       Debug.Print "The line: ", Trim(Cells(r, 1)), r
        r = r + 1
        dataMatrix(1, i) = Trim(Cells(r, 1))    ''file name
        dataMatrix(2, i) = Trim(Cells(r, 2))    ''sample type
        dataMatrix(3, i) = Trim(Cells(r, 3))    ''sample name
        dataMatrix(4, i) = "ETG"
        dataMatrix(5, i) = Trim(Cells(r, 5))    ''Response
        dataMatrix(6, i) = Trim(Cells(r, 6))    ''ISTD Response
        dataMatrix(7, i) = Trim(Cells(r, 10))   ''Calculated Conc
        i = i + 1
        ReDim Preserve dataMatrix(7, i)
    Loop

Answer 1

Redim Preserve 允许您更改数组的维度，同时保留数组的内容。

每个循环末尾的 Redim Preserve 会向数组添加另一行。

我认为第二个循环正在附加到数组，因为 i 变量在循环之间没有更改。