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I would consider creating a List containing pointers to the form instances as they are opened. If you need to reverse the process, i.e. figure out the number when you have the form, then save the number in the Tag field.
CQ de W5ALT
Walt Fair, Jr., P. E.
Comport Computing
Specializing in Technical Engineering Software
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A Dictionary<int, Form> ?
modified on Wednesday, August 3, 2011 7:49 AM
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You have two good answers, already, but I'll go ahead and ask whether the 1-20 Form instances are:
1. created when you launch the application: i.e., in the Main Form's 'Load or 'Shown Events, or as a result of parsing command line parameters ?
2. if created at run-time after the Main Form is shown, is their creation executed once and only once ... or, are they liable to be 'disposed,' and then a new set is created ?
If created at application launch, there are several strategies you could pursue, including:
1. making all the created Forms have the Main Form as their owner: then you can use the 'OwnedForms Form Collection of the Main Form to access them sequentially ... as long as the Main Form doesn't own other Forms of a different Type.
2.using the Application.OpenForms Form Collection, after the duplicate Forms have been shown, and iterating through it, testing for if (currentForm is FormForCopying) to discriminate copied Forms from other Forms.
A simpler strategy, independent of whether you create the Forms at launch, or at run-time:
1. Take your existing Form definition used for copies, make it sub-class Form, then add a public property to it of type int with getter and setter: as you create the copies assign the value you want to the public property.
I'd probably go with the strategy suggested in either Walt or Shameel's answers ... unless ... there were other compelling reasons to add additional properties, methods, special events, etc. to the copied Forms.
If one of your 'issues' is you want the end-user to be able to re-position the copied Forms on-demand at run-time, perhaps after moving them about, or whatever, you might consider caching their original positions the first time you display them, so that you can 'pop' them back into their original position without calculation ... assuming none have been deleted or added.
You could apply the same strategy for preserving the original positions of the copied Forms that you choose to preserve the numerical index of the Forms.
best, Bill
"In the River of Delights, Panic has not failed me." Jorge Luis Borges
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hi!
im using wmi for my coded project, and i need to get some data in system properties. can anyone help me how to get the values for the initial size and maximum size of the virtual memory and how to change their values.
thanks!
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<pre lang="xml">How do you dynamically assign a datagrid's headers in c#?
Consider the following XAML:
<data:DataGrid x:Name="dataGrid" AutoGenerateColumns="False" Margin="1,1,1,1" >
<data:DataGrid.Columns>
<data:DataGridTextColumn
Header="Substantive"
Binding="{Binding Path=Substantive}"
IsReadOnly="True"
/>
<data:DataGridTextColumn
Header=""
Binding="{Binding Path=Month[0]}"
IsReadOnly="True"
/>
<data:DataGridTextColumn
Header=""
Binding="{Binding Path=Month[1]}"
IsReadOnly="True"
/>
</data:DataGrid.Columns>
</data:DataGrid>
In the C# code, how would I define the headers that are blank?</pre>
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hi
i have C# program that work with access database. (i have datetime field in access - Short Date)
How to make sure that the program will not crash with the wrong date format ?
for example:
in my computer the date in this format: dd/MM/yyyy
and if i run my program on computer that has this format: MM/dd/yyyy
the program will crash or will show me abnormal result
is there any generic solution ?
can i get any C# code for this ?
thanks in advance
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This might help
http://msdn.microsoft.com/en-us/library/w2sa9yss.aspx[^]
".45 ACP - because shooting twice is just silly" - JSOP, 2010 ----- You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010 ----- "Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass." - Dale Earnhardt, 1997
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You can and should get rid of all regional setting stuff and avoid all string representations for dates, use the proper data types in your code AND in your database. This implies you use SQL parameters, not literal data.
For MS Access, use OleDbParameter (which requires the ? symbolic name in the SQL statement, where other databases would allow real symbolic names for the parameters; the question marks and parameters are synchronized in chronological order).
Example:
string SQL="UPDATE [references] SET name=?,address=?,zip_code=?,date=? WHERE referenceID = 1115224993"
OleDbCommand cmd=new OleDbCommand(...);
...
cmd.Parameters.Add("date", OleDbType.Date).Value=DateTime.Today;
...
See, no date strings at all.
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I like that!
Nice to see you around Luc.
------------------------------------
I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave
CCC Link[ ^]
Trolls[ ^]
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Dalek Dave wrote: I like that!
This ain't bloody Facebook (yet)!
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I have found that you can use @name in place of ? , which allows one to use a parameter more than once, but they still have to be in typographical order.
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I am assuming you mean the following would be good:
string SQL="UPDATE tableName SET anInt=@anInt, aString=@aString, anotherInt=@anInt, aDate=@aDate WHERE ..."
OleDbCommand cmd=new OleDbCommand(...);
cmd.Parameters.Add("@anInt", OleDbType.Int).Value=12;
cmd.Parameters.Add("@aString", OleDbType.VarChar).Value="abc";
cmd.Parameters.Add("@aDate", OleDbType.Date).Value=DateTime.Today;
as the parameters are given in the order of first use.
But then that limitation seems pretty weird, as now they use parameter names to handle duplicate uses, but not for general parameter identification? That doesn't make much sense to me. If they would use names all the way (not hard at all), it would work like T-SQL and others!?
Maybe it depends on the OleDb version, where older ones need "?" and newer ones do it the proper way? Just guessing. Do you have any reference?
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I think both uses of @anInt have to be consecutive, but it has been a while since I last experimented with it.
Luc Pattyn wrote: Do you have any reference?
Just experience.
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I just performed a simple experiment with @name and it works just fine, so now my code for Access (using Provider=Microsoft.Jet.OLEDB.4.0) and for SQLServer looks pretty much the same, except for those stupid OleDbTypes/SqlTypes enums the parameters need.
[ADDED]
The MSDN doc[^] doesn't mention named parameters in a positive way, all it says is: The OLE DB.NET Framework Data Provider uses positional parameters that are marked with a question mark (?) instead of named parameters.
[/ADDED]
Luc Pattyn [My Articles] Nil Volentibus Arduum
modified on Monday, August 1, 2011 11:05 PM
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Do I smell a Tip/trick or article in the making?
Good to see you again.
Cheers,
Peter
Software rusts. Simon Stephenson, ca 1994.
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Peter_in_2780 wrote: Do I smell a Tip/trick or article in the making?
Not really. I don't have any reference to this, and I tend not to rely on, nor propagate, undocumented ways that seem to work but aren't promised to work.
Peter_in_2780 wrote: Good to see you again
Thanks. I have reduced my presence, I'm visiting and posting sporadically now.
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Luc Pattyn wrote: those stupid OleDbTypes/SqlTypes enums the parameters need.
The what?
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cmd.Parameters.Add("@aDate", OleDbType.Date).Value=DateTime.Today;
^
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these force me to duplicate a lot of code when I need to support more than one database type (Access and SQLServer).
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I don't do it that way. I never set the type; it seems unnecessary.
Here's how I create parameters currently:
protected virtual System.Data.IDbDataParameter
AddParameter
(
string Name
,
object Value
)
{
System.Data.IDbDataParameter result = this.command.CreateParameter() ;
result.ParameterName = Name ;
result.Value = Value ;
this.command.Parameters.Add ( result ) ;
return ( result ) ;
}
(I hope to pubish my latest data access library before the end of the year.)
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Thanks Piebald, great idea of using interfaces here, it allowed me to reduce my code a lot.
I got it all working with a single IDbConnection and IDbCommand (serving either OleDb/Access or Sql/SQLServer), except for one issue: Access doesn't want to store DateTime values in Date/Time fields when using IDbCommand and CreateParameter, not even when I force the field type (with result.DBType, which is generic, not OleDb-specific). I'm getting a generic message about a criteria datatype mismatch, and all Google turns up is adding or removing quotes, which I don't have and don't want.
So I reverted to using cmd.Parameters.Add(name,type).Value=val which is target specific but works fine.
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Glad to be of service.
Luc Pattyn wrote: interfaces here, it allowed me to reduce my code
That's what they're for.
Luc Pattyn wrote: Access doesn't want to store DateTime
Huh, that's odd. I guess I haven't tried it. I'll give it a shot and see whether or not I can replicate it.
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Well, I certainly was able to replicate it.
In my derived class for OleDb, I have added:
protected override System.Data.IDbDataParameter
AddParameter
(
string Name
,
object Value
)
{
System.Data.OleDb.OleDbParameter result =
(System.Data.OleDb.OleDbParameter) base.AddParameter ( Name , Value ) ;
if ( Value is System.DateTime )
{
result.OleDbType = System.Data.OleDb.OleDbType.Date ;
}
return ( result ) ;
}
Which solved the immediate problem, but I suppose there are others out there waiting to pounce.
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Thanks for the confirmation and the suggestions, I'm good now.
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Luc Pattyn wrote: I'm good now
Don't sell yourself short.
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Since you asked, here is my next obstacle: I have a legacy Access database I want to convert to something more modern, probably SQLServer Express. The built-in "Upgrade Wizard" produced a working database, except for the primary keys: all fields of type "Autonumber" became regular integer fields, without "Identity ON". I know I could convert each table individually, adding a column, marking it identity, then force it to accept the existing values, finally removing and renaming columns. But that is so messy and cumbersome. Do you have any suggestions? or did I miss something?
TIA.
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