确定数组中的元素的数量
我意识到，标题提供了一个简单的答案。 不过，请阅读。 在我的本科学习中，我学习了一门叫做计算math和数值分析的课程，在那里我学习了C ++。 现在我开始在VBA编码 – 只是为了好玩。 我试着做一个程序，可以计算一个多项式的根。 来回之后，我设法写下了所有的代码。 我想要做的最后一件事是在Excel中打印所有的根。 为此，我使用了一个名为“arroot”的数组。 下面的Sub是我的Main：
Sub Main() Dim fx As Double, Dim dffx As Double, Dim n As Integer Dim x As Double, Dim root As Double, Dim arroot() Dim a(15) As Long, Dim i As Integer Sheet1.Cells.ClearContents Call PolyCoef(n, a) i = 0 Do Call Table(n, a, x, fx, dffx) Call NewRapHorner(n, a, fx, dffx, root) Call HornerDivPol(n, a, root) arroot(i) = root i = i + 1 Loop While (Not n = 0) Call Printroot(arroot) End Sub 你可以看到，我正在保存数组中的值，总是更新'我'，以确保我得到的每一个价值。 负责打印根的代码如下所示：
Private Sub Printroot(arroot()) Sheet1.Range("G3").Value = "Root" Sheet1.Range("H3").Value = "x-value" For i = 0 To UBound(arroot()) Step 1 Sheet1.Range("G" & 4 + i).Value = i + 1 & ". root" Sheet1.Range("H" & 4 + i).Value = arroot(i) Next End Sub
我的问题：当这样做，我遇到了问题 – 代码将无法运行。 当我将数组定义为Dim arroot（15）时，代码将起作用。 唯一的问题是，我打印了太多“i + 1”。“root”。 我该如何解决这个问题？ 我希望我的数组和根的数量一样大。 如果这样做是有道理的：我想数组的括号为空，所以它会自动调整。
先谢谢你！
编辑：
根据要求，这是完整的代码：
Sub Main() Dim fx As Double, Dim dffx As Double, Dim n As Integer Dim x As Double, Dim root As Double, Dim arroot(15) Dim a(15) As Long, Dim i As Integer Sheet1.Cells.ClearContents Call PolyCoef(n, a) i = 0 Do Call Table(n, a, x, fx, dffx) Call NewRapHorner(n, a, fx, dffx, root) Call HornerDivPol(n, a, root) arroot(i) = root i = i + 1 Loop While (Not n = 0) Call Printroot(arroot) End Sub 'Main Ends. Subs used in main are defined: Private Sub PolyCoef(n As Integer, a() As Long) Dim e As Integer Sheet1.Range("A1").Value = "Enter n for polynomial" Sheet1.Range("B1").Value = InputBox("Enter n", "Degree of the polynomial") n = Sheet1.Range("B1").Value e = n Sheet1.Range("A3").Value = "Coefficients:" Sheet1.Range("B3").Value = "Values:" For i = 0 To n Step 1 Sheet1.Range("A" & i + 4).Value = i + 1 & ". coefficient, a" & e Sheet1.Range("B" & i + 4).Value = InputBox("Enter coefficient", i + 1 & ". coefficient") a(i) = Sheet1.Range("B" & i + 4).Value e = e - 1 Next End Sub Private Sub Horner(n As Integer, a() As Long, x As Double, fx As Double, dffx As Double) Dim e As Integer, Dim b(15), Dim c(15) b(0) = a(0) For i = 1 To n Step 1 b(i) = a(i) + x * b(i - 1) Next c(0) = b(0) For i = 1 To n Step 1 c(i) = b(i) + x * c(i - 1) Next fx = b(n) dffx = c(n - 1) End Sub Private Sub Table(n As Integer, a() As Long, x As Double, fx As Double, dffx As Double) Dim xmax As Double, Dim dx As Double x = InputBox("Enter first x-value", "Enter xmin") xmax = InputBox("Enter last x-value", "Enter xmax") dx = (xmax - x) / 19 Sheet1.Range("D3").Value = "x-value" Sheet1.Range("E3").Value = "f(x)" For i = 0 To 19 Step 1 Call Horner(n, a, x, fx, dffx) Sheet1.Range("D" & 4 + i).Value = x Sheet1.Range("E" & 4 + i).Value = fx x = x + dx Next End Sub Private Sub NewRapHorner(n As Integer, a() As Long, fx As Double, dffx As Double, root As Double) Dim xnew As Double, Dim xold As Double, Dim eps As Double Dim ite As Integer, Dim x0 As Double, Dim i As Integer x0 = InputBox("Enter x-value close to root", "x-value") eps = InputBox("Enter tolerance", "Tolerance") ite = InputBox("Enter number of max iterations", "Max iterations") i = 0 xnew = x0 root = 0 Do xold = xnew Call Horner(n, a, xnew, fx, dffx) xnew = xnew - (fx / dffx) i = i + 1 Loop While (Abs(xnew - xold) > eps And i < ite) If i >= ite Then MsgBox "Number of max iterations has been exeeded" Else root = xnew End If End Sub Private Sub HornerDivPol(n As Integer, a() As Long, root As Double) Dim b(15) As Long b(0) = a(0) For i = 1 To n Step 1 b(i) = a(i) + root * b(i - 1) Next For i = 1 To n Step 1 a(i) = b(i) Next n = n - 1 End Sub Private Sub Printroot(arroot()) Sheet1.Range("G3").Value = "Root" Sheet1.Range("H3").Value = "x-value" For i = 0 To UBound(arroot()) Step 1 Sheet1.Range("G" & 4 + i).Value = i + 1 & ". root" Sheet1.Range("H" & 4 + i).Value = arroot(i) Next End Sub
数组对于你想在VBA中做什么来说效率不是很高。 我会build议创build一个集合，如：
Public yourArray As New Collection
添加相同types的元素将dynamic调整其大小。 下面我将展示如何将元素添加到集合中。
Public yourArray As New Collection Sub trieal() i = 10 Do Until i = 1 yourArray.Add i i = i - 1 Loop For Each e In yourArray Debug.Print (e) Next End Sub
这解决了你的“数组”元素循环的问题。