本人刚刚学习VB，想编一个简单的计算器程序（界面如图）
，过程中出了个问题，真的不知道出在什么地方，麻烦各位大虾帮忙解决一下，下面的是其中的一段代码，其中的linshizifu是全局变量用来存储用户点击一个数字按钮后的数字，定义的anniu变量赋了初值是0，在单击运算法则（+，-，×，÷）后anniu的值相应的变成1，2，3，4
zifu1是用来存储第一个运算数的，zifu2是用来存储第二个运算数的。例如：5+56 对应的zifu1是5 zifu2是56
用if语句判断anniu的值的情况来得知用户有没有按运算符（+，-，×，÷） 要是没按那么还是属于第一个运算数，因此用zifu1 = zifu1 & linshizifu语句来使得zifu1自动增加，要是anniu的值不是0了表示用户按了其中一个运算符号，那么对zifu2进行增加。但是运行过程中根本增加不了，zifu1和zifu2始终是空的，不知道怎么搞的。。。我调试的时候跟踪了一下zifu1,zifu2显示的是这样的：如图 我定义zifu1和zifu2的时候是这样定义的dim zifu1 as string*20 , zifu2 as string*20

Private Sub Command2_Click()
linshizifu = Command2.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub


各位给点指示吧！！！！！！！！！！！

刚学VB，还有好多不是很了解
希望各位指点指点
那个计算器我已经编好了，传上来大家看一看

Option Explicit
Dim zifu1 As String, zifu2 As String, linshizifu As String * 1, anniu%, num1#, num2#, result#
Private Sub Command1_Click()
linshizifu = Command1.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command10_Click()
linshizifu = Command10.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command11_Click()
num1 = Val(zifu1)
num2 = Val(zifu2)
Select Case anniu
Case 1
result = num1 + num2
Picture1.Print "=" & result
Case 2
result = num1 - num2
Picture1.Print "=" & result
Case 3
result = num1 * num2
Picture1.Print "=" & result
Case 4
If num2 = 0 Then
Picture1.Print " 输入错误.被除数不能为零"
Else
result = num1 / num2
Picture1.Print "=" & result
End If
Case 5
result = num1 ^ num2
Picture1.Print "=" & result
End Select

End Sub

Private Sub Command12_Click()
linshizifu = Command12.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command13_Click()
Picture1.Print Command13.Caption;
anniu = 1
End Sub

Private Sub Command14_Click()
Picture1.Print Command14.Caption;
anniu = 4
End Sub

Private Sub Command15_Click()
Picture1.Print Command15.Caption;
anniu = 3
End Sub

Private Sub Command16_Click()
Picture1.Print Command16.Caption;
anniu = 2
End Sub

Private Sub Command17_Click()
zifu1 = ""
zifu2 = ""
anniu = 0
Picture1.Cls
End Sub

Private Sub Command18_Click()
Dim a%
a = Shell("C:\Program Files\Internet Explorer\IEXPLORE.EXE", 1)
End Sub

Private Sub Command19_Click()
Dim a%
a = Shell("regedit.exe", 1)
End Sub

Private Sub Command2_Click()
linshizifu = Command2.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command20_Click()
Dim a%
a = Shell("C:\Program Files\Outlook Express\msimn.exe", 1)
End Sub

Private Sub Command21_Click()
Dim a%
a = Shell("C:\WINDOWS\explorer.exe", 1)
End Sub

Private Sub Command22_Click()
Dim a%
a = Shell("C:\Program Files\Windows Media Player\wmplayer.exe", 1)
End Sub

Private Sub Command23_Click()
Dim a%
a = Shell("C:\WINDOWS\system32\taskmgr.exe", 1)
End Sub

Private Sub Command24_Click()
Dim a%
a = Shell("C:\WINDOWS\system32\notepad.exe", 1)
End Sub

Private Sub Command25_Click()
Dim a%
a = Shell("C:\WINDOWS\pchealth\helpctr\binaries\msconfig.exe", 1)
End Sub

Private Sub Command26_Click()
linshizifu = Command26.Caption
Picture1.Print linshizifu;
anniu = 5
End Sub

Private Sub Command27_Click()
num1 = Val(zifu1)
If num1 >= 0 Then
result = Sqr(num1)
Picture1.Print "开方=" & result
Else
Picture1.Print " 负数不能开方"
End If
End Sub

Private Sub Command28_Click()
linshizifu = "-"
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command3_Click()
linshizifu = Command3.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command4_Click()
linshizifu = Command4.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command5_Click()
linshizifu = Command5.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command6_Click()
linshizifu = Command6.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command7_Click()
linshizifu = Command7.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command8_Click()
linshizifu = Command8.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Command9_Click()
linshizifu = Command9.Caption
Picture1.Print linshizifu;
If anniu = 0 Then
zifu1 = zifu1 & linshizifu
Else
zifu2 = zifu2 & linshizifu
End If
End Sub

Private Sub Form_Load()
anniu = 0
End Sub

Private Sub 打开cmd_Click()
Dim a%
a = Shell("cmd.exe", 1)
End Sub
————————————————————————————————————————————
上面是代码，由于我刚学VB 2个星期，所以好多不知道怎么弄，书一半还没看到。。。。好多算法不知道怎么实现。。。例如楼上提出的这个问题，负数先点减号不行，我当时也想用减号，但是不知道怎么写程序。。所以就另外加了一个按钮。。。。另外大家也可以从我的这个程序代码中看出，用于计算的只定义了两个变量zifu1和zifu2来记录用户输入，所以多个数同时输入的话就会接在zifu2后面，所以就出问题了。。这个问题我想通过多定义几个变量应该可以解决。。。我会继续学，然后来改进这个计算器。。。。我现在想我的这个计算器的实现算法可能不太好，由于写的时候第一想到的就是这个算法，所以就写了，现在写出来了才发现有好多弊端。。。。我会继续改进。。。也希望各位指点一下本菜鸟。。。。

再问一下，如果要在picture上实现换行，请问代码怎么写？

那个我知道啊，你理解错了我的意思了，我是说就算一次print但是当输出的东东超出了picture的边界后就换行，那个要怎么用代码实现。。。可是picture又没有自动换行的功能。。。。