frmform.frm

Visual Basic 6 大学教程的代码

VERSION 5.00
Begin VB.Form frmForm 
   Caption         =   "Fig. 14.20: Credit Inquiry Program"
   ClientHeight    =   1785
   ClientLeft      =   2460
   ClientTop       =   2745
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   1785
   ScaleWidth      =   4680
   Begin VB.CommandButton cmdButton 
      Caption         =   "Zero Balances"
      Height          =   345
      Index           =   2
      Left            =   3225
      TabIndex        =   3
      Top             =   1350
      Width           =   1335
   End
   Begin VB.CommandButton cmdButton 
      Caption         =   "Debit Balances"
      Height          =   345
      Index           =   1
      Left            =   1665
      TabIndex        =   2
      Top             =   1350
      Width           =   1335
   End
   Begin VB.CommandButton cmdButton 
      Caption         =   "Credit Balances"
      Height          =   345
      Index           =   0
      Left            =   105
      TabIndex        =   1
      Top             =   1350
      Width           =   1335
   End
   Begin VB.TextBox txtDisplay 
      Height          =   1170
      Left            =   135
      Locked          =   -1  'True
      MultiLine       =   -1  'True
      ScrollBars      =   3  'Both
      TabIndex        =   0
      TabStop         =   0   'False
      Top             =   105
      Width           =   4425
   End
End
Attribute VB_Name = "frmForm"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
' Fig. 14.20
' Credit inquiry program
Option Explicit                   ' General declaration
Dim mFso As New FileSystemObject  ' General declaration
Dim mType As Integer              ' General declaration
Const mCREDIT = 0, mDEBIT = 1, mZERO = 2  ' General declaration

Private Sub cmdButton_Click(Index As Integer)
  mType = Index   ' Assign cmdButton control array index
  Call openAndReadFile  ' Open and read file
End Sub

Private Sub openAndReadFile()
   Dim txtStream As TextStream, s As String
   Dim balance As Currency, pos As Long
   
   txtDisplay.Text = "Accounts:"
   
   ' Get "clients.dat" and open a TextStream for reading
   Set txtStream = mFso.GetFile("c:\clients.dat"). _
                   OpenAsTextStream(ForReading)
   
   ' Loop until end of stream is found
   Do
     s = txtStream.ReadLine   ' Read one line
     
     ' Find the position of the second space
     pos = InStr(InStr(1, s, " ", vbTextCompare) + 1, s, " ", _
                 vbTextCompare)
     
     ' Extract the String that contains the balance
     balance = Trim$(Mid$(s, pos, Len(s) - pos))
     
     ' Determine what if anything should be displayed
     If (mType = mCREDIT And balance < 0) Then
        txtDisplay.Text = txtDisplay.Text & vbNewLine & s
     ElseIf (mType = mDEBIT And balance > 0) Then
        txtDisplay.Text = txtDisplay.Text & vbNewLine & s
     ElseIf (mType = mZERO And balance = 0) Then
        txtDisplay.Text = txtDisplay.Text & vbNewLine & s
     End If
          
   Loop While (txtStream.AtEndOfStream = False)
      
   Call txtStream.Close     ' Close TextStream
End Sub