基于VB编写的简单计算器
今天介绍一款VB实现的简单计算器，是十年前的作品，对于初学者而言，是个很好的练手项目，感兴趣的同学可以自己动手试试。
(1)界面如下：
(2)代码如下：
Option Explicit
Dim strNumber As String
Dim strPoint As String
Dim dblNum1 As Double
Dim intOperator As Integer
'清除结果
Private Sub cmdGT_Click()
TxtDisplay.Text = "0."
strNumber = ""
strPoint = "."
intOperator = 7
End Sub
'输入数字
Private Sub cmdNumber_Click(Index As Integer)
strNumber = strNumber & cmdNumber(Index).Caption
TxtDisplay.Text = strNumber & strPoint
End Sub
'运算过程
Private Sub cmdOperator_Click(Index As Integer)
Dim dblnum2 As Double
'是第一次单击运算符时，将输入的值先赋给第一个数，否则赋值给第二个数进行运算
If intOperator = 7 Then
dblNum1 = CDbl(TxtDisplay.Text) 'CDBL是转换为双精度型
Else
dblnum2 = CDbl(Val(TxtDisplay.Text))
'根据输入的符号进行运算
'求普通运算
Select Case intOperator
Case 0
dblNum1 = dblNum1 + dblnum2
Case 1
dblNum1 = dblNum1 - dblnum2
Case 2
dblNum1 = dblNum1 * dblnum2
Case 3
If dblnum2 <> 0 Then
dblNum1 = dblNum1 / dblnum2
Else
MsgBox "除数不能为0!,请重新输入除数。", vbOKOnly + vbInformation, "除零错误"
Index = intOperator
End If
End Select
End If
'取得当前输入的运算符，以做下次运算
intOperator = Index
strNumber = ""
TxtDisplay = CStr(dblNum1)
'判断是否为文本框中的数字加点
If Not TxtDisplay Like "*.*" Then
TxtDisplay.Text = TxtDisplay.Text & "."
End If
End Sub
Private Sub cmdOtherOper_Click(Index As Integer)
Dim dblNum As Double
'求平方根，平方，
dblNum = CDbl(Val(TxtDisplay.Text))
Select Case Index
Case 0
'验证数据是否有效
If dblNum >= 0 Then
TxtDisplay.Text = CStr(Sqr(dblNum))
Else
MsgBox "负数不能开平方根！", _
vbOKOnly + vbCritical, "开平方根错误"
End If
Case 1
TxtDisplay.Text = CStr(dblNum ^ 2)
End Select
'判断是否为文本框中的数字加点
If Not TxtDisplay Like "*.*" Then
TxtDisplay.Text = TxtDisplay.Text & "."
End If
End Sub
Private Sub cmdPoint_Click()
strNumber = strNumber & strPoint
strPoint = ""
End Sub
Private Sub Form_Load()
strNumber = ""
strPoint = "."
intOperator = 7
End Sub