【Excel】VBAマクロで日付の比較（大小：今日：yyyymmddやシリアル）方法【何日間：以降だったら：今日より前の日付か判断】

Sub HikakuToHyouji()
    Dim saigoNoGyou As Long
    Dim i As Long
    Dim hizukeA As Date, hizukeB As Date
    Dim sa As Long
    
    'A列の最終行を取得
    saigoNoGyou = Cells(Rows.Count, 1).End(xlUp).Row
    
    '2行目から最終行までループ
    For i = 2 To saigoNoGyou
        '日付をyyyymmdd形式で取得
        hizukeA = DateValue(Format(Cells(i, 1).Value, "yyyy/mm/dd"))
        hizukeB = DateValue(Format(Cells(i, 2).Value, "yyyy/mm/dd"))
        
        'C列に大きい方の日付を表示
        If hizukeA > hizukeB Then
            Cells(i, 3).Value = hizukeA
        Else
            Cells(i, 3).Value = hizukeB
        End If
        
        'D列に日付の差（日数）を表示
        sa = Abs(DateDiff("d", hizukeA, hizukeB))
        Cells(i, 4).Value = sa
    Next i
End Sub

Sub KigenHantei()
    Dim saigoNoGyou As Long
    Dim i As Long
    Dim kyouNoHizuke As Date
    Dim hikakuHizuke As Date
    
    '今日の日付を取得
    kyouNoHizuke = Date
    
    'B列の最

終行を取得
    saigoNoGyou = Cells(Rows.Count, 2).End(xlUp).Row
    
    '2行目から最終行までループ
    For i = 2 To saigoNoGyou
        'B列の日付を取得
        hikakuHizuke = Cells(i, 2).Value
        
        'B列の日付が今日より前なら「期限切れ」、そうでなければ「期限前」とC列に表示
        If hikakuHizuke < kyouNoHizuke Then
            Cells(i, 3).Value = "期限切れ"
        Else
            Cells(i, 3).Value = "期限前"
        End If
    Next i
End Sub