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hi ,
i am new to this programming world...
i have been asked to create a simple VB application which uses a COM application written in vc++..
For eg., addition program..
VB gets two input. COM processes them and returns the answer to the VB and VB displays the answer.
does anyone know how to write code for that?? some tutorials or sample applications will be more helpful.
rakesh
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You have to create an instance of the COM class in your code, then you can call the methods and properties of the object. Add a reference to the COM library, under My Project, References tab.
Then you import the namespace at the top of your code. Once you have that, it's as easy as creating any other object:
Dim s As New MyComObject
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Hello all:
I am hoping someone might be able to shed some light on this!
I wanted to pass the following string as a sql query in VB6 (it is not by choice I am doing this in vb6, it is an old app)
sql = "Select enteredvalue from Eln_property_values where property_key = 2381 and section_key IN (select primary_key from eln_sections where Name = 'Version Overview Page' and section_set_key IN (select Target_key from eln_references where Collection_key = 25))"
the strange thing is when the string is created it becomes: (the issue is at the end)
sql = "Select enteredvalue from Eln_property_values where property_key = 2381 and section_key IN (select primary_key from eln_sections where Name = 'Version Overview Page' and section_set_key IN (select Target_key from eln_references where Collection_key = "
It seems to drop the value and the two parentheses. Strange??
Even stranger is if I replace "...Collection_key=25))" with ...Collection_key XYZ))" it becomes ...Collection_key XYy". I have no idea what is happening (I do not have alot of experience with VB6).
I am pretty sure I could break up the nested sql and run each select separately, but that does not seem like a great fix as there will be some unnecessary code and three recordsets opening and closing. Any help or thoughts would be most welcome,
Thank you
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My guess is that strings are limited to 255 chars.
But it's quite a while since I did VB6 that I can't remember. 
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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riced-
Thank you for the response, I think you may be right. I thought this might be a possibility but was not sure with my limited vb6 exposure. I guess it is time to break this string up,
Thanks again
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I don't think that is correct... limitation on string length certainly does not explain why the last "Z" became a "y"!
IIRC, VB6 strings are 64k in length. Text fields in MS Access (not sure about the version...) are limited to 255 char.
HTH
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ChandraRam-
Agreed. But the 255 limit did get me on the correct path. I did some further digging within the application and found that the string itself is preserved during the pass, but in fact the Watch window itself only displays 255 characters and will mutate a string that is longer than that.
Thank you for all the replies...
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@ChandraRam: No, There is no 64 K limit. If you like, try in a new, empty project, the following code snippet in "Form1"
Option Explicit
Private Sub Form_Load()
Dim str As String
Dim i As Integer
str = "x"
For i = 1 To 30
str = str & str
Debug.Print Len(str)
Next i
End Sub
my string grewed was 130 million characters in size, before an error occured.
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hi ..
modified 28-Nov-12 8:21am.
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Your code makes two assumptions:.
1. The file is sorted so that similar records follow one another and are in date order.
2. There will only be two similar records in the file.
The first is obviously incorrect given the sample input. The second might be incorrect, not enough information to tell.
There is also a problem with your date comparison. It is actually comparing two string variables (dateTime and dateTime1). This means that 01/06/2009 comes before 30/05/2009, so you will get the wrong date (assuming that not all creation days are the same).
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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To compare the date fields you need to convert them to Date variables, something like
Dim created As Date
Dim created1 As Date
created = CDate(dateTime)
created1 = CDate(dateTime1)
and then compare created with created1.
vijay2482 wrote: There many be many conditions like this.
Does this mean that the comparisons (other than the dates) might be different?
In other words 'What is it that makes two lines count as similar'?
There's two possible approaches to the problem that I can see, both involve the use of a list.
1. Read the whole file into a list, sort the list, remove the unwanted lines, then write the list out to file. This would mean that the output lines are not necessarily in the same order as the input lines. If that is important it can be got around.
2. Read the input a line at a time. Check if the list contains a matching record. If it does not, add the line to end of list. If it does, check the dates, if the line just read is earlier than the one in list do nothing otherwise replace the list entry. When all lines have been read, output the list.
Either approach is best done using a typed list and an appropriate structure or class to hold a data line. I can't think of a way that your existing code could be modified to deal with this problem.
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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Are you using CDate(dateTime) as in example?
You can't do this: created = dateTime. But you should be able to do this created = CDate(dateTime) provided dateTime holds a string that is a valid date/time.
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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I did point this out when I said that your code relied on two assumptions (one being that similar lines are together when the example shows this is not the case).
There's a problem in the logic you describe since you would need to wind the input file back to line 4. Can't be done without closing and reopening the file and reading through from the start ignoring lines until you get to line 4.
You need to read the file into a list: either sorting it after reading the whole file, or checking for matches as each line is read.
I suppose you could use your logic if you read the file into an array of strings and dealt with it that way.
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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It's easy to read a file into an array (use ReadAllLines) and to sort the array (use Array.Sort(yourArray)). But that's where your problems start. This simple approach won't work with your data. You would need to use Array.Sort(yourArray, yourComparer) and doing this will be messy. You have to define a class that implements IComparer (i.e. implements the Compare method). You then have to loop through the array and write it out while dropping duplicates. There is a problem with this approach if the output lines should be in the same order as the input (unless your compare method is clever enough to maintain order).
An alternative is to create a List(Of T) and populate the list as you read through the file. However, you can't use string for the T; you would have to define a suitable type.When each line is read in you can check if there's a match in the list. If there is you either ignore the line or update the created date field. When you have finished reading the file, you then loop through the list writing it to output.
There are other possible ways to solve the problem e.g. you could define a class that has a string property and overrides the Equals method to allow comparisons.
Given some of the problems you have raised (and what I infer about your knowledge of VB.NET), I think you are going to find this difficult.
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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Hi to All
I have a few doubts on creation of process to execute any exe/ppt/any file in VB.NET. Please clarify me
1) How to use waitforexit() methods. Its not working for me in some cases?
My code is..
dim p as new process
p.startInfo.filename=MyPath
p.start()
p.waitforexit()
Sometimes If I run a calc, (ie MyPath is either calc.exe or a path to a shortcut of calc)..It runs the calc and shows an error in p.waitforexit() saying something like "p has not assign any process"
2)Can we check for an process if it is alive? I want to check if explorer.exe is running?
3)Can we maximise and bring it to front of the all window, for a process which is running? (eg: I have a form which covers the desktop. I have a button(run calc) which runs calculator..Now after running if I click on the form,the calc goes back to my form...Now if I click the button(run calc),I dont want to open a new calc,...instead I want to bring the already running calc on top.)
Thnaks in advance
-----------------------------
I am a beginner
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p.startInfo.filename=MyPath
p.start()
If (!p.HasExited && p.Responding) Then
p.waitforexit()
End If
himangshuS wrote: 2)Can we check for an process if it is alive?
Yes. Check out the <a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.hasexited.aspx">HasExited</a>[<a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.hasexited.aspx" target="_blank" title="New Window">^</a>] and the <a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.responding.aspx">Responding</a>[<a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.responding.aspx" target="_blank" title="New Window">^</a>] properties.
himangshuS wrote: 3)Can we maximise and bring it to front of the all window, for a process which is running?
Yes. You'll have to get the handle to the mainform, based on the proces-id. Then you can set the WindowState and you can BringToFront the Window 
I are troll
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thnaks for your reply..
About my first doubt,...fine I will execute your code and see. But Could you please tell me what could be the problem in the line p.waitforexit()...that happen only sometimes,spexially when I run calc.
About my second problem:: How do I check for the process explorer.exe? Could u please a sample code, Since I will have to get the process id for explorer.exe or something like that?
For the third one...Are you talking about the handle of my application window or the proicess window ie calc?...Also How will I get to know the exact process Id?..since if I can run calc more then one time...how will i get process id for each one?
thanks
-----------------------------
I am a beginner
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himangshuS wrote: About my first doubt,...fine I will execute your code and see. But Could you please tell me what could be the problem in the line p.waitforexit()...that happen only sometimes,spexially when I run calc.
It may already have been terminated, or just too busy to proces incoming messages.
himangshuS wrote: About my second problem:: How do I check for the process explorer.exe? Could u please a sample code, Since I will have to get the process id for explorer.exe or something like that?
Use the <a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.aspx">Process</a>[<a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.aspx" target="_blank" title="New Window">^</a>] class to get a list of all running processes.
' Start Explorer.
Dim p As Process
p = Process.Start("explorer.exe")
MessageBox.Show(p.Id)
himangshuS wrote: since if I can run calc more then one time...how will i get process id for each one?
Well, you get an Id each time you start "calc.exe" through the Process class. Your best option would be to keep a list around of the processes that you started. I wouldn't close any of the processes that you didn't start yourself; the end-user might be really confused if his/hers calculator suddenly dissapears.
I are troll
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You're calling WaitForExit before the process even has a chance to start. Starting a new process is a very expensive call. The Start method does not wait for the process to completely start before returning.
It's up to you to wait for the app to start, by calling p.WaitForInputIdle before you call the WaitForExit method.
himangshuS wrote: Now if I click the button(run calc),I dont want to open a new calc,...instead I want to bring the already running calc on top.)
Then you have to check to see if it's still running (the user may have closed it), relaunch it if needed, easily done using the Process class. If it's still running, then you can get the ProcessId from its Process object, than pass that to AppActivate to bring it to the front.
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thanks
Could you please help me with the code since I have very less idea about the process class an all.
In order to maximise or bring the already running calc/any process to front
thanks
-----------------------------
I am a beginner
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I'm not writing your code for you.
Check out the Process.GetProcessesByName method.
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