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。https://www.360docs.net/doc/1c8238094.html,/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

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

blnMinuse = True

End If

Next i

If blnMinuse = True Then

vParam2 = -vParam2

End If

Select Case mstrOperate

Case "+"

vResult = vParam1 + vParam2

Case "-"

vResult = vParam1 - vParam2

Case "*"

vResult = vParam1 * vParam2

Case "/"

vResult = vParam1 / vParam2

End Select

txtOperate.Text = txtOperate.Text & "=" & vbCrLf

strResult = Format(vResult, mstrFORMATDEFAULT)

txtShow.Text = strResult

txtOperate.Text = txtOperate.Text & strResult & vbCrLf

End Sub

Private Sub Form_Load()

txtShow.Text = ""

txtOperate.Text = ""

End Sub

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