[VB6 ] 計算機程式問題

[suiming (台灣fighting!)]

松崗的書的例子f10_7_2
1.請問42行為什麼If後不用加end if
2.每一段的select case是啥意思?opt不是要先指定嗎?為什麼opt都放最後?


Name        Caption
txtBoard        －
cmdNum(0)       0
cmdNum(1)       1
cmdNum(2)       2
cmdNum(3)       3
cmdNum(4)       4
cmdNum(5)       5
cmdNum(6)       6
cmdNum(7)       7
cmdNum(8)       8
cmdNum(9)       9
cmdDot          .
cmdAdd          +
cmdSub          -
cmdCancel       C
cmdAns          =
cmdEnd        Off

程式碼
 1 Dim opt As Integer
 2 Dim total As Double, temp_val As Double
 3 Dim dot As Single, zero As Single
 4 Const Nul = 0, Add = 1, Subb = 2, Ans = 3

 5 Private Sub cmdAdd_Click()
 6　Select Case opt
 7　　Case Nul: total = temp_val
 8　　Case Add: total = total + temp_val
 9　　Case Subb: total = total - temp_val
10　　Case Ans: total = temp_val
11　End Select
12　txtBoard = Str(total)
13　temp_val = 0
14　opt = Add
15 End Sub

16 Private Sub cmdAns_Click()
17　Select Case opt
18　　Case Nul: total = temp_val
19　　Case Add: total = total + temp_val
20　　Case Subb: total = total - temp_val
21　　Case Ans: total = temp_val
22　End Select
23　txtBoard = Str(total)
24　temp_val = 0
25　opt = Ans
26 End Sub

27 Private Sub cmdCancel_Click()
28　opt = Nul
29　total = 0
30　temp_val = 0
31　txtBoard.Text = Str(temp_val)
32 End Sub

33 Private Sub cmdDot_Click()
34　dot = True
35 End Sub

36 Private Sub cmdEnd_Click()
37　End
38 End Sub

39 Private Sub cmdNum_Click(index As Integer)
40　If dot = True Then
41　　temp_val = Val(Str(temp_val) + "." + Str(index))
42　　If index = 0 Then zero = True
43　　dot = False
44　Else
45　　If zero = True Then
46　　　temp_val = Val(Str(temp_val) + ".0" + Str(index))
47　　　zero = False
48　　Else
49　　　temp_val = Val(Str(temp_val) + Str(index))
50　　End If
51　End If
52　txtBoard.Text = Str(temp_val)
53 End Sub

54 Private Sub cmdSub_Click()
55　Select Case opt
56　　Case Nul: total = temp_val
57　　Case Add: total = total + temp_val
58　　Case Subb: total = total - temp_val
59　　Case Ans: total = temp_val
60　End Select
61　txtBoard = Str(total)
62　temp_val = 0
63　opt = Subb
64 End Sub

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※ 編輯: suiming (39.12.215.94), 07/19/2014 21:06:52
→ tsongs:If index = 0 Then zero = True 一行寫完的確不用 End If
→ tsongs:Dim opt As Integer ,opt是變數
→ tsongs:Select Case 跟if類似 你先讀懂Select Case語法
→ tsongs:Select Case opt
→ tsongs:　Case Nul: total = temp_val
→ tsongs:跟 if opt = Nul then   同意思
→ tsongs:跟 if opt = Nul then  temp_val 同意思
→ MOONRAKER:最好你的松肛書上沒有select case用法的咧