frmreading.frm

Visual Basic 6 大学教程的代码

VERSION 5.00
Object = "{C932BA88-4374-101B-A56C-00AA003668DC}#1.1#0"; "MSMASK32.OCX"
Begin VB.Form frmReading 
   Caption         =   "Fig. 14.19: Reading from a sequential file"
   ClientHeight    =   2685
   ClientLeft      =   2715
   ClientTop       =   2460
   ClientWidth     =   4785
   LinkTopic       =   "Form1"
   ScaleHeight     =   2685
   ScaleWidth      =   4785
   Begin VB.Frame Frame1 
      Caption         =   "Account Information"
      Height          =   2055
      Left            =   90
      TabIndex        =   1
      Top             =   75
      Width           =   3210
      Begin VB.TextBox txtBalance 
         Height          =   375
         Left            =   1050
         Locked          =   -1  'True
         TabIndex        =   8
         Top             =   1545
         Width           =   1980
      End
      Begin VB.TextBox txtName 
         Height          =   375
         Left            =   1050
         Locked          =   -1  'True
         TabIndex        =   7
         Top             =   952
         Width           =   1980
      End
      Begin MSMask.MaskEdBox mskAccount 
         Height          =   375
         Left            =   1050
         TabIndex        =   6
         Top             =   360
         Width           =   1980
         _ExtentX        =   3493
         _ExtentY        =   661
         _Version        =   393216
         Enabled         =   0   'False
         Format          =   "###"
         PromptChar      =   "_"
      End
      Begin VB.Label lblBalance 
         Caption         =   "Balance:"
         Height          =   390
         Left            =   135
         TabIndex        =   4
         Top             =   1560
         Width           =   1110
      End
      Begin VB.Label lblName 
         Caption         =   "Last Name:"
         Height          =   360
         Left            =   120
         TabIndex        =   3
         Top             =   975
         Width           =   1335
      End
      Begin VB.Label lblAccount 
         Caption         =   "Account:"
         Height          =   315
         Left            =   150
         TabIndex        =   2
         Top             =   435
         Width           =   1350
      End
   End
   Begin VB.CommandButton cmdRead 
      Caption         =   "Read"
      Height          =   495
      Left            =   3465
      TabIndex        =   0
      Top             =   1650
      Width           =   1215
   End
   Begin VB.Label lblFileName 
      BorderStyle     =   1  'Fixed Single
      Height          =   345
      Left            =   90
      TabIndex        =   5
      Top             =   2280
      Width           =   4590
   End
End
Attribute VB_Name = "frmReading"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
' Fig. 14.19
' Reading from a sequential text file
Option Explicit                          ' General declaration
Dim mFileSysObj As New FileSystemObject  ' General declaration
Dim mFile As File                        ' General declaration
Dim mTxtStream As TextStream             ' General declaration

Private Sub Form_Load()

   ' Get the file
   Set mFile = mFileSysObj.GetFile("..\clients.dat")
   
   ' Open a text stream for writing to the file
   Set mTxtStream = mFile.OpenAsTextStream(ForReading)
   
   ' Display path in lblFileName
   lblFileName.Caption = mFile.Path
End Sub

Private Sub cmdRead_Click()
   Dim s As String
   
   On Error GoTo handler   ' Set error trap
   
   ' Read the data
   s = mTxtStream.ReadLine
                                                        
   ' Parse String s to get values for MaskEdit
   ' and TextBoxes
   Dim mark1 As Integer, mark2 As Integer
   
   mark1 = 4   ' Location of first space in s
      
   ' Place only the String portion representing the
   ' account in the MaskEdit.
   mskAccount.Text = Trim$(Mid$(s, 1, mark1))
      
   ' Position to first letter of name
   mark1 = mark1 + 1
   
   ' Determine location of second space character and
   ' add 1 to include the space.
   mark2 = InStr(mark1, s, " ", vbTextCompare) + 1
   
   ' Place only the String portion representing the
   ' name in the TextBox.
   txtName.Text = Trim$(Mid$(s, mark1, mark2 - mark1))
   
   ' Place the formatted dollar amount in the TextBox.
   ' mark2 is positioned at the beginning of the amount.
   txtBalance.Text = Format$(Mid$(s, mark2, Len(s) - mark1), _
                             "Currency")
   Exit Sub
   
handler:

   If Err.Number = 62 Then      ' EOF error
      Call mTxtStream.Close
      cmdRead.Enabled = False
      lblFileName.Caption = ""
   Else
      Call MsgBox(Err.Description)
   End If
   
End Sub