有一个Byte数组A，如果我们知道这个数组上限最大只能是4，就用Dim

　　Dim A As Byte(4)

　　但如果我们不能事先确定它的大小，或者需要在运行时改变它的大小就要用动态数组

　　Dim A As Byte()

　　ReDim A(4) 这样改变大小时会清空原来的数据

　　ReDim Preserve A(4) 这样改变大小时会保留原来的数据-There is a Byte array of A, if we know that the array can only be a maximum ceiling of 4, you use Dim Dim A As Byte (4) However, if we do not pre-determine its size, or need to change it at runtime must use the size of the dynamic array Dim A As Byte () ReDim A (4) ' This will change the size of the original data in clear ReDim Preserve A (4)'　This change will retain the original size of the data