计算机等级考试二级VB常用算法:进制转化

3/18/2007来源:软件水平考试人气:16300

  1、算法说明

  1) 十进制正整数m转换为R(2-16)进制的字符串。

  思路: 将m不断除r取余数,直到商为0,将余数反序即得到结果。

  算法实现:

以下是引用片段:
  PRivate Function Tran(ByVal m As Integer, ByVal r As Integer) As String
  Dim StrDtoR As String, n As Integer
  Do While m <> o
  n = m Mod r
  m = m \ r
  If n > 9 Then
  StrDtoR = Chr(65 + n - 10) & StrDtoR
  Else
  StrDtoR = n & StrDtoR
  End If
  Loop
  Tran = StrDtoR
  End Function


  2) R(2-16)进制字符串转换为十进制正整数。

  思路:R进制数每位数字乘以权值之和即为十进制数。

  算法实现:

以下是引用片段:
  Private Function Tran(ByVal s As String, ByVal r As Integer) As integer
  Dim n As Integer, dec As Integer
  s = UCase(Trim(s))
  For i% = 1 To Len(s)
  If Mid(s, i, 1) >= "A" Then
  n = Asc(Mid(s, i, 1)) - Asc("A") + 10
  Else
  n = Val(Mid(s, i, 1))
  End If
  dec = dec + n * r ^ (Len(s) - i)
  Next i
  Tran = dec
  End Function


  解题技巧

  进制转化的原理要清楚,同时编写代码时候要留意16进制中的A-F字符的处理。
  2、实战练习

  1) 补充代码

  本程序是把给定的二进制整数转换为八进制整数。

以下是引用片段:
  Private Sub Command1_Click()
  Dim a As String, b As String, c As String
  Dim L As Integer, m As Integer, n As Integer
  a = InputBox("请输入一个二进制数", "输入框")
  (1)
  a = String(L, "0") & a
  (2)
  For m = 1 To n / 3
  b = Mid(a, 3 * m - 2, 3)
  (3)
  Next m
  Text1.Text = c
  End Sub
  Private Function zh(s As String) As String
  Dim i As Integer, n As Integer, p As Integer
  p = 1
  For i = 2 To 0 Step -1
  (4)
  p = p + 1
  Next i
  zh = Str(n)
  End Function


  2) 补充代码

  下面程序是把给定的16进制正整数转换为10进制数。 以下是引用片段:
  Option Explicit
  Private Sub Form_Click()
  Dim St As Integer, Dem As Long
  St=InputBox("输入一个十六进制数")
  Dem=Convert(St)
  Print St; ">="; Dem
  End Sub
  Private Function Convert(S As String)As Long
  Dim N As Integer, I As Integer,Substring As String*1
  Dim P As long, K As Long,Asc1 As Integer
  N= (1)
  P=16^N
  For I=1 To N
  P=P/16
  Substring= (2)
  Select Case Substring
  Case "0" To "9"
  K=K+P*Val(Substring)
  Case (3)
  Asc1=Asc(Substring)-Asc("A")+10
  (4)
  End Select
  Next I
  (5)