VBA SUM可變範圍

Question

我想要一個代碼來將變量行加起來，如果滿足某些條件。 例如如果A12是數字並且B12是空的，則在單元格C12中插入一個公式以便求和C3：C11。 然後在C22和C30執行相同的操作。 我遇到的問題是不知道如何定義起始行。

Sub Test() 
Dim y As Variant 
Dim r As Variant 
Dim StartRow As Variant 

    LastRow = Range("C" & Rows.Count).End(xlUp).Row 
     For y = 3 To 500 
      For r = 1 To LastRow 

      If InStr(1, Cells(r, 1), "Amount") Then 
       StartRow = r 

      If IsNumeric(Cells(y, 1)) And IsEmpty(Cells(y, 2)) Then 
      Cells(y, 3).Formula = "=SUM(C" & StartRow + 1 & ":C" & y - 1 & ")" 
      End If 
     End If 
     Next r 
    Next y 

End Sub 

Answer 1

Sub Test() 
Dim y As Variant 
Dim firstRow As Variant 
Dim lastRow As Variant 
lastRow = Range("C" & Rows.Count).End(xlUp).Row 
firstRow = Cells(lastRow, 3).End(xlUp).Row 
If IsNumeric(Cells(lastRow + 1, 1)) And IsEmpty(Cells(lastRow + 1, 2)) Then 
    Cells(lastRow + 1, 3).Formula = "=SUM(C" & firstRow & ":C" & lastRow & ")" 
End If 
For y = firstRow To 3 Step -1 
    lastRow = Cells(y, 3).End(xlUp).Row 
    firstRow = Cells(lastRow, 3).End(xlUp).Row 
    If firstRow < 3 Then firstRow = 3 
    If IsNumeric(Cells(lastRow + 1, 1)) And IsEmpty(Cells(lastRow + 1, 2)) Then 
     Cells(lastRow + 1, 3).Formula = "=SUM(C" & firstRow & ":C" & lastRow & ")" 
    End If 
    y = firstRow 
    If firstRow = 3 Then Exit Sub 
    Next y 
End Sub