对比2个表数据

Sub CompareData()
    Dim arrA() As Variant
    Dim arrC() As Variant
    
    Dim rowA As Long
    Dim rowC As Long
    
    '获取A列和C列的最后一行行号
    rowA = Cells(Cells.Rows.Count, 1).End(xlUp).Row
    rowC = Cells(Cells.Rows.Count, 3).End(xlUp).Row
    
    '将A列和C列的数据存放到数组中
    arrA = Range("A1").Resize(rowA, 1).Value
    arrC = Range("C1").Resize(rowC, 1).Value
    
    '声明存储结果的数组
    Dim result() As Variant
    '数组使用一定要明确定义大小
    '结果数组肯定不会超过C列的数据数量，所以可以定义结果行的最大下标为rowC
    ReDim result(1 To rowC, 1 To 1) As Variant
    
    '记录标题
    result(1, 1) = arrC(1, 1)
    
    '记录结果数据的个数
    Dim resultCount As Long
    resultCount = 1 '标题占用1个
    
    '用循环找出列C中不在列A中出现的数据
    Dim i As Long, j As Long
    '数据是从第2行开始的
    For i = 2 To rowC
        '判断C列的每一个数据在A列中是否出现了
        For j = 2 To rowA
            '判断是否相同
            If arrA(j, 1) = arrC(i, 1) Then
                '如果相同就可以提前退出A列的循环了
                'Exit For退出最近的那个For循环
                Exit For
            End If
        Next
        '如果A列不是Exit For结束的，这时候j的值会等于rowA+1
        If j = rowA + 1 Then
            '说明是在A列没有出现的数据，记录下来
            resultCount = resultCount + 1 '结果的数量增加1
            result(resultCount, 1) = arrC(i, 1)
        End If
    Next
    
    '输出结果
    Range("E1").Resize(resultCount, 1).Value = result
End Sub