Preventing multiple instances of your app from running may not enough. This small code snip will prevent multiple instances as well as duplicates from opening.
'**************************************
'Windows API/Global Declarations for :Absolutely no alias or multiple instances
'**************************************
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Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
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'**************************************
' Name: Absolutely no alias or multiple instances
' Description:Preventing multiple instances of your app from running may not enough. This small code snip will prevent multiple instances as well as duplicates from opening.
' By: Aliasace
'
' Assumes:Coder knows the forms "Class Name", and forms caption property is initially set to nullstring.
'
'This code is copyrighted and has' limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=1063&lngWId=1'for details.'**************************************
Sub Form_Load()
'--------------------------------------------------------------------------
'Form1 Caption property should be set to NullStr
'--------------------------------------------------------------------------
If App.PrevInstance Or FindWindow("ThunderRT5Form", App.Title) > 0 Then
AppTitle$ = App.Title
App.Title = "#$#"
Form1.Caption = "#$#"
AppActivate AppTitle$
End
End If
Form1.Caption = App.Title
End Sub
Answer to Kali, it called ThunderRT5Form because VB5 default handle use this name say as an internal, if you use VB6 then what? ThunderRT6Form! you right! (If this comment was disrespectful, please report it.)
If the previous instance is minimized this code will cause a crash! Look at this link for a perfect solution: http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=21131&l ngWId=1 (If this comment was disrespectful, please report it.)
Is there a similar way of using "App.PrevInstance", because my visual basic editor does not recognize it? (If this comment was disrespectful, please report it.)
2/16/2003 2:48:06 PM:
merve, VB apps won't recognise App.PrevInstance when you run them from the IDE... so you need to compile first. (If this comment was disrespectful, please report it.)
7/8/2004 12:41:20 PM:
Great code! This did EXACTLY what I needed, and it was simple and small. Thanks! (If this comment was disrespectful, please report it.)
All right, a harder problem, how do you prevent previous instances across a network when your app is on the server?
(If this comment was disrespectful, please report it.)
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