VB6.0的小程序 计算器
对于刚入门学习VB6的朋友来说肯定会做些小程序吧，这里就是给大家演示个简单的计算器程序，仅供参考啦。
界面上加减乘除四个按钮分别是cmdAdd、cmdPlus、cmdMultiple、cmdDevide，小数点按钮是cmdDot，负号按钮是cmdMinuse，数字0～9为了偷懒，用了控件数组cmdNumber(0)~ cmdNumber(9)，上面txtShow是显示数字和结果用的，txtOperate是显示中间步骤的。
思路大致是这样，点加减乘除这类操作符的时候，把当前txtShow的值保存在模块变量mstrParam1里，同时把操作符保存到mstrOperate里，按等于号时把先把当前txtShow的值保存在模块变量mstrParam2里，然后对mstrParam1和mstrParam2进行运算，当然要记得设法把String转换成数值进行运算。
转换的过程要注意，这里是用的Variant数据类型，vParam1和vParam2都是Variant类型，保存的是mstrParam1和mstrParam2的数值。之所以不用integer、long、double这些标准类型，是因为这些类型都有大小限制，做出来用着不方便，VB最大的整型long才到 2147483647，
这意味着计算器的计算结果只能限制在9位到10位。而Variant类型可以支持非常大的数，具体多大不清楚，但起码几十位是能够支持的。另外，最后算完的结果也要做格式化，因为如果数值非常大的话，VB会自动转成科学计数法，所以要用Format函数进行调整。
如果需要源代码的话在我百度空间里留言。hi.baidu/zhaozhigang517
Option Explicit
Private Const mstrFORMATDEFAULT As String = "#.##"
Private mstrParam1 As String, mstrParam2 As String
Private mstrOperate As String
Private Sub cmdAdd_Click()
mstrParam1 = Trim(txtShow.Text)
mstrOperate = "+"
txtShow.Text = ""
txtOperate.Text = txtOperate.Text & mstrParam1 & vbCrLf
txtOperate.Text = txtOperate.Text & mstrOperate & vbCrLf
End Sub
Private Sub cmdPlus_Click()
mstrParam1 = Trim(txtShow.Text)
mstrOperate = "-"
txtShow.Text = ""
txtOperate.Text = txtOperate.Text & mstrParam1 & vbCrLf
txtOperate.Text = txtOperate.Text & mstrOperate & vbCrLf
End Sub
Private Sub cmdMultiple_Click()
mstrParam1 = Trim(txtShow.Text)
mstrOperate = "*"
txtShow.Text = ""
txtOperate.Text = txtOperate.Text & mstrParam1 & vbCrLf
txtOperate.Text = txtOperate.Text & mstrOperate & vbCrLf
End Sub
Private Sub cmdDevide_Click()
mstrParam1 = Trim(txtShow.Text)
mstrOperate = "/"
txtShow.Text = ""
txtOperate.Text = txtOperate.Text & mstrParam1 & vbCrLf
txtOperate.Text = txtOperate.Text & mstrOperate & vbCrLf
End Sub
Private Sub cmdDot_Click()
Dim mstrShow As String
Dim i As Integer
mstrShow = "."
i = InStr(1, txtShow.Text, mstrShow)
If i <= 0 Then
txtShow.Text = txtShow.Text & mstrShow
End If
End Sub
Private Sub cmdMinuse_Click()
Dim mstrShow As String
Dim i As Integer
mstrShow = "-"
i = InStr(1, txtShow.Text, mstrShow)
If i <= 0 Then
txtShow.Text = mstrShow & txtShow.Text
Else
vb计算器代码大全 txtShow.Text = Right(txtShow.Text, Len(txtShow.Text) - 1)
End If
End Sub
Private Sub cmdNumber_Click(Index As Integer)
Dim mstrShow As String
mstrShow = Index
txtShow.Text = txtShow.Text & mstrShow
End Sub
Private Sub cmdClear_Click()
txtShow.Text = ""
End Sub
Private Sub cmdResult_Click()
Dim vParam1 As Variant, vParam2 As Variant
Dim vResult As Variant
Dim strResult As String
Dim i As Long
Dim blnBeforeDot As Boolean
Dim lngDotPos As Long
Dim blnMinuse As Boolean
mstrParam2 = Trim(txtShow.Text)
txtOperate.Text = txtOperate.Text & mstrParam2 & vbCrLf
vParam1 = 0
blnBeforeDot = True
lngDotPos = -1
blnMinuse = False
For i = 1 To Len(mstrParam1)
If IsNumeric(Mid(mstrParam1, i, 1)) = True Then
If blnBeforeDot = True Then
vParam1 = vParam1 * 10 + CByte(Mid(mstrParam1, i, 1))
Else
vParam1 = vParam1 + CByte(Mid(mstrParam1, i, 1)) * (0.1 ^ (i - lngDotPos))
End If
ElseIf Mid(mstrParam1, i, 1) = "." Then
blnBeforeDot = False
lngDotPos = i
ElseIf Mid(mstrParam1, i, 1) = "-" Then
blnMinuse = True
End If
Next i
If blnMinuse = True Then
vParam1 = -vParam1
End If
vParam2 = 0
blnBeforeDot = True
lngDotPos = -1
blnMinuse = False
For i = 1 To Len(mstrParam2)
If IsNumeric(Mid(mstrParam2, i, 1)) = True Then
If blnBeforeDot = True Then
vParam2 = vParam2 * 10 + CByte(Mid(mstrParam2, i, 1))
Else
vParam2 = vParam2 + CByte(Mid(mstrParam2, i, 1)) * (0.1 ^ (i - lngDotPos))
End If
ElseIf Mid(mstrParam2, i, 1) = "." Then
blnBeforeDot = False
lngDotPos = i
ElseIf Mid(mstrParam2, i, 1) = "-" Then
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