form1.frm

Visual Basic程序设计基础》-杨小影-源代码

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3885
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   5535
   LinkTopic       =   "Form1"
   ScaleHeight     =   3885
   ScaleWidth      =   5535
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton Command1 
      Caption         =   "计算阶乘"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   18
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   1095
      Left            =   3240
      TabIndex        =   2
      Top             =   960
      Width           =   2055
   End
   Begin VB.TextBox Text1 
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   15
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   1095
      Left            =   240
      TabIndex        =   1
      Top             =   960
      Width           =   2535
   End
   Begin VB.Label Label3 
      Caption         =   "Label3"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   14.25
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   855
      Left            =   240
      TabIndex        =   4
      Top             =   3000
      Width           =   2655
   End
   Begin VB.Label Label2 
      Caption         =   "Label2"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   14.25
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   855
      Left            =   240
      TabIndex        =   3
      Top             =   2280
      Width           =   2535
   End
   Begin VB.Label Label1 
      Caption         =   "请输入（0-20）之间整数"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   14.25
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   1095
      Left            =   240
      TabIndex        =   0
      Top             =   120
      Width           =   3615
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False

Function checkparameters()
'将用户输入转化为数值参数
x = Val(Text1.Text)
'检查用户输入是否有效
'如果输入错误，则提示用户重新输入
'输入正确，就把检查过的参数作为结果返回
If x > 20 And x < 0 Then
Label2.Caption = "输入错误！请重新输入！"
'清除标签上以前显示的结果
'并返回一个非正数值
Label3.Caption = " "
checkparameters = -1
Else
checkparameters = x
Label2.Caption = "结果是:"
End If
End Function
Function jiecheng(ByVal x As Integer) As Long
If x = 0 Or x = 1 Then
  jiecheng = 1
 Else
jiecheng = x * jiecheng(x - 1)
End If
End Function

Private Sub command1_click()
retV = checkparameters()
If retV >= 0 Then
Label3.Caption = Str$(jiecheng(retV))
End If
End Sub