Question

VB题，重点解释下For i = 1 To UBound(b) b(i) = 2 * b(i)那里

Private Sub pl(b() As Integer)
For i = 1 To UBound(b)
b(i) = 2 * b(i)
Next i
End Sub
Private Sub Command1_Click()
Dim a(1 To 3) As Integer
Dim i%, s%
For i = 1 To 3
a(i) = i + 3
Next i
Call pl(a())
For i = 1 To 3
s = s + a(i)
Next i
Print a(3)
Print s
End Sub
答案 12 30

Answer 1

Private Sub pl(b() As Integer)
For i = 1 To UBound(b) 'ubound(b)即返回一个 Long 型数据，其值为指定的数组维可用的
最大下标即3,该句等同于 for i=1 to 3
b(i) = 2 * b(i) '把传过来的数组a(1 to 3)逐个*2
Next i
End Sub

Private Sub Command1_Click()
Dim a(1 To 3) As Integer
Dim i%, s%
For i = 1 To 3
a(i) = i + 3
Next i '到这步 a(1)=4,a(2)=5,a(3)=6
Call pl(a()) '到这步 a(1)=8,a(2)=10,a(3)=12
For i = 1 To 3
s = s + a(i)
Next i '到这步 s=a(1)+a(2)+a(3)=30
Print a(3)

Print s
End Sub
答案 12 30

追问

UBound(b)=3 怎么来的？

追答

ubound(b)的意思是b数组的最大下标,b数组是command1_click中a数组传递而来,Dim a(1 To 3) As Integer,所以b数组的下标为1 to 3,b的最大下标=3,即ubound(b)=3

Answer 2

UBound（b）这个函数作用是找到B数组的最大下标来控制循环次数的，b(i) = 2 * b(i)是让数组的数自身乘以2，i是数组下标，来控制不同的数