form1.frm

Visual Basic 6 网络编程实例教程ch01～ch02分别包含了书中各章的主要程序文件

VERSION 5.00
Begin VB.Form Form1 
   BorderStyle     =   1  'Fixed Single
   Caption         =   "网络域名"
   ClientHeight    =   1950
   ClientLeft      =   45
   ClientTop       =   330
   ClientWidth     =   3180
   Icon            =   "Form1.frx":0000
   LinkTopic       =   "Form1"
   MaxButton       =   0   'False
   MinButton       =   0   'False
   ScaleHeight     =   1950
   ScaleWidth      =   3180
   StartUpPosition =   1  '所有者中心
   Begin VB.CommandButton CmdGetDomainName 
      Caption         =   "运行(&R)"
      Default         =   -1  'True
      Height          =   495
      Left            =   960
      TabIndex        =   2
      Top             =   1200
      Width           =   1215
   End
   Begin VB.TextBox TxtDomainName 
      Height          =   375
      Left            =   720
      TabIndex        =   1
      Text            =   "TxtDomainName"
      Top             =   600
      Width           =   1935
   End
   Begin VB.Label Label1 
      AutoSize        =   -1  'True
      Caption         =   "网络域名："
      Height          =   180
      Left            =   480
      TabIndex        =   0
      Top             =   240
      Width           =   900
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit

Private Sub CmdGetDomainName_Click()
    TxtDomainName = GetDomainName()
End Sub

Private Function GetDomainName() As String
    Dim buff()        As Byte
    Dim cbRequired    As Long
    Dim nStructSize   As Long
    Dim Info          As FIXED_INFO
    '以空pFixedInfo参数调用api函数
    '这样该API函数会返回存放数据所需的缓存大小，
    '该值被保存在参数cbRequired中
    Call GetNetworkParams(ByVal 0&, cbRequired)
    If cbRequired > 0 Then
        '创建所需大小的缓存
        ReDim buff(0 To cbRequired - 1) As Byte
        '再一次调用API函数
        If GetNetworkParams(buff(0), cbRequired) = ERROR_SUCCESS Then
            '拷贝该缓存中的数据为FIXED_INFO类型
            CopyMemory Info, ByVal VarPtr(buff(0)), LenB(Info)
            '返回主机名称
            GetDomainName = TrimNull(StrConv(Info.DomainName, vbUnicode))
        End If
    End If
End Function

Private Function TrimNull(item As String)
Dim pos As Integer
'检查字符串中是否有chr$(0)字符)(即空字符)
pos = InStr(item, Chr$(0))
If pos Then
    TrimNull = Left$(item, pos - 1)
Else: TrimNull = item
End If
End Function