Question

vb整数溢出怎么处理

我想生产均匀分布的随机数，程序如下：
Private Sub Cd1_Click()
Open "E:\随机数论文\均匀随机数1.txt" For Output As #1
Dim i As Integer, x, s As String
Const m = 2 ^ 31 - 1, a = 16807
Static xi As Double
For i = 1 To 10000
Randomize
x = Int(Rnd * (2 ^ 31))
s = a * x
xi = CLng(s - 2 ^ 32) Mod CLng(m)
u1 = xi / m
Write #1, u1
Next
Close #1
End Sub
总是提示溢出，请问怎么解决？

Answer 1

VB 里 Long 所能表示的最大值是 2^31 - 1, 2147483647

For i = 1 To 10000
Randomize
x = Int(Rnd * (2 ^ 31))
s = a * x
xi = CLng(s - 2 ^ 32) Mod CLng(m)

s - 2 ^ 32 已经超过了 2147483647
CLng(s - 2 ^ 32) 变换为 Long 型 当然要溢出了
只能用 Single 或 Double

Answer 2

Dim i As Double