From the past to the future, from Visual and Basic to Net
Small god 2001.08.08
The initial VB was called "Thunder" plan as a MS. It was started in 1990. At that time, Gates also personally wrote a written written in the magazine, telling people "Gates on Basic's Future; 10 years later, VB) In development and change, it is now called "vb.net". Gates still writes in the magazine for VB, telling people "How VB Will Program The Future", I think Gates I have prevailing the Basic language. Not only him, there are many people who are also preferred in Bill and VB. In fact, half of this world is using this language, and in China is almost 80% of the program developers in use, but there is also a fact that VB's actual usage is declining, because of proficiency The programmers of multiple languages are casually switched out in C, C , Java, and Script language. The mature programmers are no longer arguing the programming language, but according to the application itself, it needs to be implemented according to the industry standard. No matter what language you use, the key is whether your implementation complies with the standard or agreement of this industry.
Java brings us a cup of hot drink five years ago, the coffee inside made the entire network is exciting; if the VB in the transformation after five years, if the VB in the transformation is like a cup of ore, it is a bit of malnutrition. What about health? I hope it is still simple and visualized. Maybe Bill wants to tell you: Basic language is not only Visaul's and Basic, but now is NET.
New VB. What is NET? Will it be better than I am using VB6, let's take a look, and quickly master the 12 techniques.
1. Object-oriented changes, maybe it wants to be more objects, because it is not, just say that you are object-oriented. VB starts from 4.0 that it is object-oriented, and there is a somewhat suspicious .CLS file, although we use this .cls file with our DB or business layer components, there is no doubt and worry If you are used to you, you will feel that a copy is much better than C , really do you think?
Past VB
============================================================================================================================================================================================================= ====
Private M_VBProperty As Variant
Public property Let VBProperty (Byval Strdata As Variant)
m_vbproperty = strdata
End Property
Public property set vbproperty (Byval Strdata As Variant)
m_vbproperty = strdata
End Property
Public property get vbproperty () As Variant
IF isobject (m_vbproperty) THEN
SET VBPROPERTY = M_VBPROPERTY
Else
Vbproperty = m_vbproperty
END IF
End Property is currently VB. Net
============================================================================================================================================================================================================= ====
Private M_VBNETPROPERTY AS STRING
Public property VBNetProperty As String
Get
VBNetProperty = m_vbnetproperty
END GET
Set
m_vbnetproperty = VBNetProperty
End set
End Property
New adding readonly and writeonly keywords to implement function that you define read-only or only write, let and set are no longer supported. Previous set objb = Obja now produces a syntax error, you want to write in VB.NET: objb = obja
2. Reading files, the file access in VB is different, 3.0, 4.0, 5.0 are changed, and the FileSystemObject appearance allows us to have a seemingly constant object to remember, but #, the $ symbol is always letting I think of a black hole feeling. Dangerous and dark, fooled these very fast. The following code completes the open WIN.INI file from the system directory and display it into a Text control.
Past VB
============================================================================================================================================================================================================= ====
Private submmand1_click ()
DIM FNUM AS INTEGER
DIM S As String
DIM FNAME AS STRING
Dim WinPath As String
ON Error Goto ErrreadTextFile
Fnum = freefile
'get the windows folder name
WinPath = Environ $ ("SystemRoot")
IF WinPath = "" ""
Msgbox "Unable to Retrieve The Windows Path.", _
Vbinformation, "ERROR READING Windows Path"
EXIT SUB
END IF
'Create a File Name
FNAME = WinPath & "/win.ini"
'EnSure the file exists
IF DIR $ (FNAME) <> "" "" "
'Open the file
Open fname for binary as #fnum
IF err.number = 0 THENS = Space $ (Lof (fnum))
'Read the file
Get #fnum, 1, s
Close #fnum
Text1.text = s
Else
Text1 = "Unable to read the file" & _
FNAME & "."
END IF
Else
TEXT1 = "The file" & fname "
END IF
EXITREADTEXTFILE:
EXIT SUB
ErrReadTextFile:
MsgBox Err.Number & ":" & Err.Description
EXIT SUB
End suend Sub
Now VB. Net
============================================================================================================================================================================================================= ====
Private sub btnreadtextfile_click (byval sender _
As system.object, byval e as system.eventargs _
Handles btnreadtextfile.click
Dim WinPath As String
DIM S As String
DIM FNAME AS STRING
DIM SR AS StreamReader
DIM EX AS EXCEPTION
'get the windows folder name
WinPath = system.environment. _
Getenvironmentvariable ("SystemRoot")
IF WinPath = "" ""
MessageBox.show ("Unable to Retrieve THE" & _
"Windows Path.", "Error
Reading
Windows path ", _
MessageboxButton.ok, MessageBoxicon.information)
Return
END IF
FNAME = WinPath & "/win.ini"
IF file.exists (fname) THEN
Try
SR = file.opentext (fname)
S = Sr.ReadToend
Sr.close ()
TextBox1.text = s
Catch EX
Messagebox.show (ex.Message)
Return
END TRY
Else
MessageBox.show ("The File" & FName & _
"does not exist.")
Return
END IF
End Sub
New messagebox.show is better than MessageBox, and Sr.Close () is more objects than Close #filenum.
3. Multiple choices of ListBox. How do I know that those options in a multi-selected listbox are selected. Take a look at the implementation below, although I don't like the Redim of VB, but sometimes I can really solve the problem soon. In VB.NET, you can use the data you need directly. Past VB
============================================================================================================================================================================================================= ====
Private subdgetListSelections_Click ()
DIM I as integer
DIM SARR () AS String
DIM SELCOUNT AS INTEGER
For i = 0 to list1.listcount - 1
If List1.Selected (i) THEN
Redim Preserve Sarr (SELCOUNT) AS STRING
SARR (SELCOUNT) = List1.list (i)
SELCOUNT = SELCOUNT 1
END IF
NEXT
Call showStringArray (SARR)
End Sub
Private Sub ShowstringArray (Arr () AS String)
DIM S As String
DIM I as integer
DIM Arrcount AS Integer
ON Error ResMe next
Arrcount = ubound (arr) 1
ON Error Goto 0
IF arrcount> 0 THEN
For i = 0 TO Arrcount - 1
S = S & Arr (I) & VBCRLF
NEXT
Msgbox S
END IF
End Sub
Now VB.NET
============================================================================================================================================================================================================= ====
Private sub btngetListSelections_Click (Byval Sender_
As system.object, byval e as system.eventargs _
Handles btngetListSelections.click
Dim Sarr (listbox1.selecteditedItems.count - 1) _
As string
DIM ANITEM AS STRING
DIM I as integer
For Each AnItem in listbox1.selecteditems
SARR (i) = AnItem
i = 1
NEXT
End Sub
Private Sub ShowstringArray (Byval Arr () AS STRING
Messagebox.show (Join (Arr, _system.environment.newline))
End Sub
END CLASS
4. How to start another program in the VB program, wait and know when it exits. No VB. Before NET, this problem is a professional practice. Like many problems, VB does not solve it. It is necessary to call some rare known functions. MS collects such problems, called MS Knowledge Base, should now be Called MSDN Knowledge Base, maybe you have guessed that you have to use the shell function, the past VB is waiting to be taken like our investment stocks on how to wait for the launch program and get the exit. The past VB =============================================== ======= You can get help and code in the following URL. http://support.microsoft.com/support/kb/articles/q129/7/96.asp
Now VB.Net =============================================== ========= Private Sub btnLaunch_Click (ByVal sender As _ System.Object, ByVal e As System.EventArgs) _ Handles btnLaunch.Click Dim sysPath as String sysPath = System.Environment.GetFolderPath _ (Environment.SpecialFolder. System) shell (syspath & "/notepad.exe ", _ appwinstyle.normalfocus, true) messageBox.show (" You Just Closed Notepad ", _" Notepad Closed ") End Sub's new VB.NET has become synchronized. Two programs are in a process space.
