VB 回忆录(二)——计算器

这是自己当时做的比较大一些的程序了。当时费了我不少的时间和精力，不过最后的突破还是在一个月黑风高的夜晚。

在这个程序中，可以说将上个程序的核心思路使用的很泛滥，就是用一些变量来表示程序当前的状态，比如当前是再输入第一个数，还是第二个数，或者是已经输入完成，马上就要计算结果等等。

其实，要做一个计算器，也不是一件容易的事。如果我们仔细用一下，就会发现计算器并不是我们想的简单计算一下就可以了。做一个仿真的计算器，在许多细节上要花费不少功夫，最简单的，除数位0时的判断。其他的，比如，当连加时，从第二个加号开始，没按一个加号，就要把上一次的结果计算出来。还比如，对于数字的整数部分，最高位上，是不允许输入0的，等等。

这是我第一个花费了不少精力做出来的程序，当时颇有成就感。

这个程序使我的逻辑思维得到了不少的锻炼。

题外话：在高中的时候，我就用gv-basic些过一些小程序，当时就会使用if 、do loop 等这些简单的控制语句，当时我最大的困惑就是对变量的定义很不理解，当然也不会使用。

现在回想起来，要是没有当时的这些锻炼以及“成就”对我的兴趣的激发，我以后的vb学习很可能就会停滞不前了。

这是主要的界面：

部分代码如下：

在这段代码中，我还是没有命名、缩进、注释等的习惯，所以还是有写乱。不过，只有乱过了，才会不乱。

Dim z As Byte,a As Double,b As Double,y As Byte,w As Byte,v As Byte 'z判断运算符，y判断是否按了“=”号,w防止二次按=,v判断怎样输入.

Private Sub Command1_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "1" '输入1
a = Val(Text1.Text)
End Sub

Private Sub Command10_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "0" '输入0
a = Val(Text1.Text)
End Sub

Private Sub Command11_Click() '运算=
y = 1
If w = 1 Then
Select Case z
Case Is = 1
If -10 ^ 150 > b + a Or b + a > 10 ^ 150 Then Text1.Text = "数据过大" Else Text1.Text = Str(b + a)
Case Is = 2
If -10 ^ 150 > b - a Or b - a > 10 ^ 150 Then Text1.Text = "数据过大" Else Text1.Text = Str(b - a)
Case Is = 3
If -10 ^ 150 > b * a Or b * a > 10 ^ 150 Then Text1.Text = "数据过大" Else Text1.Text = Str(b * a)
Case Is = 4
If a = 0 Then Text1.Text = "除数为零" Else If -10 ^ 150 > b / a Or b / a > 10 ^ 150 Then Text1.Text = "数据过大" Else Text1.Text = Str(b / a) '判断除数是否为零
Case Is = 5
If -10 ^ 150 > b * a Or b * a > 10 ^ 150 Then Text1.Text = "数据过大" Else Text1.Text = Str(a * b)
Case Is = 6
If b = 0 And a <= 0 Then Text1.Text = "真数为零" Else If -10 ^ 150 > b ^ a Or b ^ a > 10 ^ 150 Then Text1.Text = "error" Else Text1.Text = Str(b ^ a)
End Select
a = Val(Text1.Text): b = 0
End If

w = 0
z = 0
v = 0
End Sub

Private Sub Command12_Click()
w = 1
v = 0
y = 1
z = 1 '运算符+
b = a
End Sub

Private Sub Command13_Click()
w = 1
v = 0
y = 1
z = 2 '运算-
b = a
End Sub

Private Sub Command14_Click()
w = 1
v = 0
y = 1
z = 3 '运算*
b = a
End Sub

Private Sub Command15_Click()
w = 1
v = 0
y = 1
z = 4 '运算/
b = a
End Sub

Private Sub Command16_Click()
Text1.Alignment = 1
z = 0
w = 0
v = 0
Text1.Text = "0" '运算清除
a = 0: b = 0
End Sub

Private Sub Command17_Click()
y = 0
w = 1
If v = 1 Then Text1.Text = Text1.Text + "." Else Text1.Text = "0." '输入.
End Sub

Private Sub Command18_Click() '平方运算
w = 1
v = 0
y = 1
z = 5
b = a
End Sub

Private Sub Command19_Click() '多次方运算
w = 1
v = 0
y = 1
z = 6
b = a
End Sub

Private Sub Command2_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "2" '输入2
a = Val(Text1.Text)
End Sub

Private Sub Command3_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "3" '输入3
a = Val(Text1.Text)
End Sub

Private Sub Command4_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "4" '输入4
a = Val(Text1.Text)
End Sub

Private Sub Command5_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "5" '输入5
a = Val(Text1.Text)
End Sub

Private Sub Command6_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "6" '输入6
a = Val(Text1.Text)
End Sub

Private Sub Command7_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "7" '输入7
a = Val(Text1.Text)
End Sub

Private Sub Command8_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "8" '输入8
a = Val(Text1.Text)
End Sub

Private Sub Command9_Click()
v = 1
w = 1
If y = 1 Then Text1.Text = "": y = 0
If Text1.Text = "0" Then Text1.Text = "" '防止多余的零
Text1.Text = Text1.Text + "9" '输入9
a = Val(Text1.Text)
End Sub
Private Sub Form_Load()
Text1.Text = 0
w = 1
y = 0
z = 0
v = 0
End Sub