第7章编程第1题.frm

一本学习Visual Basic编程的好书

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   2160
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   5415
   LinkTopic       =   "Form1"
   ScaleHeight     =   2160
   ScaleWidth      =   5415
   StartUpPosition =   3  '窗口缺省
   Begin VB.TextBox Text4 
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   3720
      TabIndex        =   4
      Text            =   " "
      Top             =   1440
      Width           =   975
   End
   Begin VB.CommandButton Command1 
      Caption         =   "检验"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   12
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   3720
      TabIndex        =   3
      Top             =   480
      Width           =   975
   End
   Begin VB.TextBox Text3 
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   1680
      TabIndex        =   2
      Text            =   "  "
      Top             =   1440
      Width           =   975
   End
   Begin VB.TextBox Text2 
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   1680
      TabIndex        =   1
      Text            =   " "
      Top             =   840
      Width           =   975
   End
   Begin VB.TextBox Text1 
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   375
      Left            =   1680
      TabIndex        =   0
      Text            =   " "
      Top             =   240
      Width           =   975
   End
   Begin VB.Label Label4 
      Caption         =   "结果"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   3240
      TabIndex        =   8
      Top             =   1560
      Width           =   615
   End
   Begin VB.Label Label3 
      Caption         =   "文本框3"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   840
      TabIndex        =   7
      Top             =   1560
      Width           =   855
   End
   Begin VB.Label Label2 
      Caption         =   "文本框2"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   840
      TabIndex        =   6
      Top             =   960
      Width           =   975
   End
   Begin VB.Label Label1 
      Caption         =   "文本框1"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   840
      TabIndex        =   5
      Top             =   360
      Width           =   855
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
    Dim a As String, b As String, c As String
    a = Trim(Text1.Text)
    b = Trim(Text2.Text)
    c = Trim(Text3.Text)
    If che(a) And che(b) And che(c) Then
        Text4.Text = Val(a) + Val(b) + Val(c)
    Else
        Text4.Text = "存在非数字字符"
    End If
End Sub

Function che(x As String) As Boolean
    che = True
    For k = 1 To Len(x)
        s = Mid(x, k, 1)
        If s < "0" Or s > "9" Then
            che = False
            Exit For
        End If
    Next k
End Function