calculater.txt

适用于初学者学习

建立14个按钮，按钮的名字都要Command1，设置Index属性，0~9分别对应数字0~9，10为小数点，11为等号，12~14分别对应+、-、*和/。 
2、输入如下代码： 
Dim Num1, Num2 As Single 
Dim StrNum1, StrNum2 As String 
Dim FirstNum As Boolean 
Dim PointFlag As Boolean 
Dim Runsign As Integer 
Dim SignFlag As Boolean 
Private Sub Command1_Click(Index As Integer) 
Select Case Index 
Case 0 To 9 
If FirstNum Then 
StrNum1 = Str(Index) 
FirstNum = False 
Else 
StrNum1 = LTrim(StrNum1) + LTrim(Str(Index)) 
End If 
Text1.Text = Val(StrNum1) 
Case 10 
If Not PointFlag Then 
If FirstNum Then 
StrNum1 = "0." 
FirstNum = False 
Else 
StrNum1 = LTrim(StrNum1) + LTrim(".") 
End If 
Else 
Exit Sub 
End If 
PointFlag = True 
Text1.Text = Val(StrNum1) 
Case 12 To 15 
FirstNum = True 
PointFlag = False 
If SignFlag Then 
Call Run 
Else 
SignFlag = True 
StrNum2 = StrNum1 
StrNum1 = "" 
End If 
Runsign = Index - 11 
Case 11 
On Error Resume Next 
If Not SignFlag Then 
Text1.Text = StrNum1 
equal = Val(StrNum1) 
FirstNum = True 
PointFlag = False 
Else 
Call Run 
SignFlag = False 
End If 
Case Else 
Call ClearData 
End Select 
End Sub 
Private Sub Form_Load() 
If App.PrevInstance Then MsgBox "请不要多次运行此程序，谢谢！", vbAbortRetryIgnore: Unload Me 
Num1 = 0 
Num2 = 0 
StrNum1 = "" 
StrNum2 = "" 
FirstNum = True 
PointFlag = False 
Runsign = 0 
SignFlag = False 
End Sub 
Sub Run() 
On Error Resume Next 
Dim equal As Single 
Dim equal2 As Double 
Num1 = Val(StrNum2) 
Num2 = Val(StrNum1) 
Select Case Runsign 
Case 1 
equal = Num1 + Num2 
If Num1 >= 65536 Or Num2 >= 65536 Or equal >= 65536 Then 
equal = 0 
equal2 = Num1 + Num2 
End If 
Case 2 
equal = Num1 - Num2 
If Num1 >= 65536 Or Num2 >= 65536 Or equal >= 65536 Then 
equal = 0 
equal2 = Num1 - Num2 
End If 
Case 3 
equal = Num1 * Num2 
If Num1 >= 65536 Or Num2 >= 65536 Or equal >= 65536 Then 
equal = 0 
equal2 = Num1 * Num2 
End If 
Case 4 
equal = Num1 / Num2 
If Num1 >= 65536 Or Num2 >= 65536 Or equal >= 65536 Then 
equal = 0 
equal2 = Num1 / Num2 
End If 
End Select 
If equal = 0 Then a = equal2 Else a = equal 
StrNum2 = Str(a) 
StrNum1 = StrNum2 
Text1.Text = Val(StrNum2) 
End Sub 
Sub ClearData() 
Num1 = 0 
Num2 = 0 
StrNum1 = "" 
StrNum2 = "" 
FirstNum = True 
PointFlag = False 
Runsign = 0 
SignFlag = False 
Text1.Text = 0 
End Sub