Visual Basic中,对于文本比较好的处理方式.

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3195
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   3195
   ScaleWidth      =   4680
   StartUpPosition =   3  '窗口缺省
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Form_load()
    Dim x As Single, y As Single, i As String
    On Error GoTo errln     '以下出错时转移到errln
    Show
    i = ""                  '实数标记
    x = Val(InputBox("请输入一个数"))
    y = Sqr(x)
    Print y; i
    Exit Sub                '退出过程
errln:                      '标号
    If Err.Number = 5 Then  '本错误的错误码为5
        x = -x              '转换为正数
        i = "i"             '复数标记
        Resume              '返回
    Else                    '其他错误处理
        MsgBox ("错误发生在" & Err.Source _
            & ", 代码为" & Err.Number _
            & ", 即" & Err.Description)
        End
    End If
End Sub