primtabl.bas

一个VB小程序,能够进行大数的计算,可以作为学习的参考

Attribute VB_Name = "PrimTabl"
Attribute VB_Description = "Prints all primes in primflgs.bin. Output file will be large."
'Author : Sjoerd.J.Schaper - [e-mail]
'URL    : http://largeint.sourceforge.net/index.html
'Date   : 24-05-2004
'Code   : Visual Basic for Windows 5.0
Option Explicit

Sub PTable()
  Dim c As Long, cf As Long, cx As Long, g As String
  On Error GoTo errhand
  Key = 0: tim = Timer
  '
  Lognr = FreeFile
  Open WrkD + "primtabl.log" For Output As Lognr
  cx = PrimCeil
  If cx = 0 Then
     Data = "empty primelist: press sieve"
  Else
     Data = " Creating prime table..." + vbCrLf
     PrimList.Box.Text = Data: DoEvents
     Print #Lognr, " pi(x)  : x"
     Print #Lognr, 1; Tab(9); ":"; Tab(10); Nxtprm(0)
     c = 1
     Do
        c = c + 1: cf = Nxtprm(1)
        If cf > cx Then Exit Do
        Print #Lognr, c; Tab(9); ":"; Tab(10); cf
     Loop
     Data = Data + " Done" + vbCrLf
   End If
'
eind:
  g = vbCrLf & "Timer: " & CSng(Timer - tim) & "s"
  Data = Data & g
  PrimList.Box.Text = Data
  Print #Lognr, g
  Close Lognr: Data = ""
  On Error GoTo 0
  Exit Sub
break:
  Data = Data & " break, P = " & Nxtprm(1) & vbCrLf
  GoTo eind
errhand:
  MsgBox "PrimTabl", 48, "Error"
  Resume eind
End Sub