查找日期并清除目标单元格下方的内容

Question

我有一个循环遍历一列的宏，该列保存从旧到最近的日期。它找到每个大于

Now

的日期，然后转到其相邻单元格并清除它们。

我相信，如果宏不会针对列（500 行）中的所有值循环，而是在第一个单元格匹配处停止，然后转到其相邻单元格并清除从该行到底部的所有内容，速度会快得多表的内容（即，如果匹配位于第 15 行，则清除从第 15 行一直到 500 的内容），而不检查每一行。

    Dim R As Long

    For R = 1 To 500
        If Cells(R, "A").Value >= Now Then Cells(R, "B").Value = ""
        If Cells(R, "A").Value >= Now Then Cells(R, "C").Value = ""
    Next

End Sub 

Answer 1

使用您的方法，如果您想知道如何在条件匹配后退出循环 - 您可以使用

Exit For

。您还可以同时清除 B 列和 C 列，如下所示：

Dim R As Long
With ActiveWorkbook.Sheets("Sheet1")
    For R = 1 To 500
      If .Cells(R, "A").Value >= Now Then
          .Range("B" & R & ":C500").ClearContents
          Exit For
      End If
    Next
End With

在上面，我还添加了对该表的引用。一旦有不止一张纸可用，这始终是防止可能出现错误的良好做法。

Answer 2

这是一个二分搜索的示例。

Option Explicit

Public Sub ClearByDates(Optional targetDate As Variant = Null)

  Dim thisSheet As Worksheet
  Dim activeRange As Range
  Dim lowerRow As Long, higherRow As Long, thisRow As Long
  Dim thisDate As Date

  ' If no date is provided, assume today is the cutoff

  If IsNull(targetDate) Then targetDate = Date
  ' Assuming that we're putting this code in the worksheet that you want to _
    clear. If you decide to put it in a separate module you can either: _
      (1) Pass in the worksheet you want to modify as an argument, or _
      (2) Explicitly set the worksheet you want to modify using ActiveWorkbook.Worksheets(Name)

  Set thisSheet = Me
  Set activeRange = thisSheet.UsedRange
 
  With activeRange
  ' Not only is it cleaner if you use With, you get better performance in VBA _
    because it's a hint that the object should be kept loaded and ready.

  ' Getting the range of rows with values
    lowerRow = .Rows(1).Row
    higherRow = lowerRow + activeRange.Rows.Count - 1
   
  ' Don't start processing until you're in the date range; _
    this should handle most common worksheet header situations.
    Do Until IsDate(activeRange.Cells(lowerRow, 1))
      lowerRow = lowerRow + 1
      If lowerRow > higherRow Then Exit Sub
    Loop
   
  ' Use a binary search to find the first row where the date is _
    greater than or equal to the target date.
   
    Do Until lowerRow >= higherRow - 1
      thisRow = (higherRow + lowerRow) / 2
      thisDate = .Cells(thisRow, 1)
      Debug.Print "Row " & Right("      " & thisRow, 7) & ": " & Format(thisDate, "YYYY-MM-DD") & " ";
      If thisDate >= targetDate Then
        Debug.Print ">= " & Format(targetDate, "YYYY-MM-DD");
        higherRow = thisRow
      Else
        Debug.Print "<  " & Format(targetDate, "YYYY-MM-DD");
        lowerRow = thisRow
      End If
      Debug.Print " (lowerRow = " & lowerRow & ", higherRow = " & higherRow & ")"
    Loop
 
  ' Assuming we just want to clear columns B & C. This can easily be adjusted _
    to clear all columns to the right by using .Columns(.Columns.Count) in the _
   ending range.
  thisSheet.Range("B" & thisRow & ":C" & .Rows(.Rows.Count).Row).ClearContents
 
  End With
 
End Sub