用VBS精确计算2的100次方的代码

既然Python可以计算2的100次方，那么我就要用VBS实现。不过这个效率嘛，计算2的10000次方Python用了0.009013秒，VBS用了120.9805秒，不是一个等级的，我就不多说什么了。

直接上代码：


复制代码 代码如下:

‘Date: 2010/10/27

‘Author: Demon

‘QQ: 380401911

‘E-mail: still.demon@gmail.com

begin = Timer

n = 1

For i = 1 To 100

n = multiple(n, 2)

Next

finish = Timer

WScript.Echo n

WScript.Echo finish – begin

‘Grade school multiplication, Algorithm 14.12

‘http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf

Function multiple(byVal x, byVal y)

Dim n, t, i, j, z, w()

n = Len(x) – 1

t = Len(y) – 1

ReDim w(n + t + 1)

x = CStr(x) : y = CStr(y)

For i = 0 To UBound(w)

w(i) = “0”

Next

For i = 0 To t

Dim c : c = 0

Dim uv : uv = 0

For j = 0 To n

uv = (w(i+j)-“0”) + c + _

(Mid(x,n-j+1,1)-“0”) * (Mid(y,t-i+1,1)-“0”)

w(i+j) = CStr(uv Mod 10 + “0”)

c = uv \ 10

Next

w(i+n+1) = CStr(uv \ 10 + “0”)

Next

z = Join(w,””)

z = StrReverse(z)

Do While Left(z,1) = “0”

z = Mid(z,2)

Loop

multiple = z

End Function

原文：http://demon.tw/programming/vbs-long-multiplication.html
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