dynamic.frm

Visual Basic 6 大学教程的代码

VERSION 5.00
Begin VB.Form frmDynamic 
   Caption         =   "Fig. 7.14: Dynamic Arrays"
   ClientHeight    =   2490
   ClientLeft      =   2040
   ClientTop       =   2415
   ClientWidth     =   4620
   LinkTopic       =   "Form1"
   ScaleHeight     =   2490
   ScaleWidth      =   4620
   Begin VB.CommandButton cmdErase 
      Caption         =   "Erase"
      Enabled         =   0   'False
      Height          =   495
      Left            =   3255
      TabIndex        =   5
      Top             =   1320
      Width           =   1215
   End
   Begin VB.CheckBox chkPreserve 
      Caption         =   "Preserve"
      Height          =   495
      Left            =   3255
      TabIndex        =   4
      Top             =   1800
      Width           =   1215
   End
   Begin VB.CommandButton cmdPrint 
      Caption         =   "Display"
      Height          =   495
      Left            =   3255
      TabIndex        =   2
      Top             =   720
      Width           =   1215
   End
   Begin VB.ListBox lstValues 
      Height          =   1620
      Left            =   30
      TabIndex        =   3
      Top             =   720
      Width           =   3045
   End
   Begin VB.TextBox txtInput 
      Height          =   405
      Left            =   2850
      TabIndex        =   0
      Top             =   120
      Width           =   1215
   End
   Begin VB.Label lblPrompt 
      Caption         =   "Enter array size and press Display:"
      Height          =   285
      Left            =   300
      TabIndex        =   1
      Top             =   180
      Width           =   2520
   End
End
Attribute VB_Name = "frmDynamic"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
' Fig. 7.14
' Demonstrating dynamic arrays
Option Explicit
Option Base 1
Dim mDynamic() As Integer

Private Sub cmdErase_Click()
   Erase mDynamic        ' Free memory
   Call lstValues.Clear
   cmdErase.Enabled = False
   chkPreserve.Value = vbUnchecked  ' Uncheck Preserve
End Sub

Private Sub cmdPrint_Click()
   Dim arrayLength As Integer, x As Integer
   
   Call lstValues.Clear
   arrayLength = txtInput.Text
   
   ' Determine state of CheckBox
   If chkPreserve.Value = vbUnchecked Then   ' Unchecked
      ReDim mDynamic(arrayLength)             ' Allocate memory
      Call InitArray                         ' Initialize to defaults
   ElseIf chkPreserve.Value = vbChecked Then ' Checked
      ' Allocate memory and preserve contents
      ReDim Preserve mDynamic(arrayLength)
   End If
   
   ' Display index and array contents in ListBox
   For x = LBound(mDynamic) To UBound(mDynamic)
      Call lstValues.AddItem("Index: " & x & vbTab & _
                        vbTab & "Value: " & mDynamic(x))
   Next x
   
   cmdErase.Enabled = True
End Sub

Private Sub InitArray()
   Dim x As Integer
   
   ' Generate some data
   For x = LBound(mDynamic) To UBound(mDynamic)
      mDynamic(x) = Int(51 * Rnd())
   Next x
   
End Sub