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You'll have to work around the problem a bit. You could make dbColumn abstract with object ColumnValueAsObject, and then a typedDBColumn< T > with T ColumnValue returning ColumnValueAsObject cast to T.
Then you can have a list of dbColumns which you can iterate and do ColumnValueAsObject.ToString() on.
This doesnt have much more functionality than a DataSet in the end. You are basically shifting the cast based on the column type you would have to do into picking the right templated call...
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I think I don't understand your suggestion.
I try to made this property abstract but this don't solve my trouble.
It may return object, and not specific return type.
May you give a sample code?!?
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Greeg pretty much covered a similar idea using an interface below.
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What you could do for instance would be something like this using generics:
class dbColumn<T,U> {
private string pColumnName;
private T pColumnValue;
private U pColumnType;
public string ColumnName{
get{
return pColumnName;
}
set{
pColumnName = value;
}
}
public T ColumnValue{
get{
return pColumnValue;
}
set{
pColumnValue = value;
}
}
public U ColumnType{
get{
return pColumnType;
}
set{
pColumnType = value;
}
}
public dbColumn(string colName, T colValue, U colType){
this.pColumnName = colName;
this.pColumnValue = colValue;
this.pColumnType = colType;
}
}
Not tested, but you get the idea.
regards
modified 12-Sep-18 21:01pm.
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Thanks for you reply.
This is similar to what I had tried to do....
But using dbColumn<t> [or as you just suggested dbColumn<t,u>] instead of dbColumn I cannot create a List<dbcolumn> cause I may use this sintax List<dbcolumn><[specifictype]>>.
So i cannot create a list of different column to use for example as I made in my first post code for create a query.
<br />
List<dbcolumn> columns = new List<dbcolumn>();<br />
foreach (dbColumn col in columns){<br />
col.ColumnName + "="+ columnValue<br />
}
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True. What you might try is inheriting your column type classes from a common abstract class or interface, like
interface IAbstractColumnType
{
}
class MyColumnType : IAbstractColumnType
{
...
}
And then create a List like that:
List<IAbstractColumnType>
regards
modified 12-Sep-18 21:01pm.
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You are suggesting to use different class for each type?
I think there something wrong:
I must add ColumnValue and ColumnName to interface (or i cannot use them in foreach loop)
So i must implement "object ColumnValue" and I cannot hide ColumnValue property using new for changing return type.
Here's sample code [which has error]
<br />
class dbTable{<br />
List<IAbstractColumnType> columns = new List<IAbstractColumnType>();<br />
<br />
public void GetSelectQuery(){<br />
string sql = "";<br />
foreach (IAbstractColumnType col in columns){<br />
sql +=col.ColumnName + "=" + col.ColumnValue;<br />
}<br />
return sql;<br />
}<br />
}<br />
<br />
public interface IAbstractColumnType {<br />
object ColumnValue;<br />
object ColumnName;<br />
}<br />
<br />
<br />
public class dbColumn {<br />
private string _Column;<br />
public string ColumnName {<br />
get {<br />
return _Column;<br />
}<br />
set {<br />
_Column = value;<br />
}<br />
}<br />
}<br />
<br />
public class dbColumnInt : dbColumn, IAbstractColumnType {<br />
private int _Value;<br />
public new int ColumnValue {<br />
get {<br />
return _Value;<br />
}<br />
set {<br />
_Valore = value;<br />
}<br />
}<br />
public dbColumnInt(string column, int id) {<br />
this._Value = id;<br />
}<br />
<br />
}<br />
<br />
public class dbColumnString : IAbstractColumnType {<br />
private string _Value;<br />
public new string ColumnValue {<br />
get {<br />
return _Value;<br />
}<br />
set {<br />
_Value = value;<br />
}<br />
}<br />
public dbColumnString(string column, string testo) {<br />
this._Value = testo;<br />
}<br />
}
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i'm getting this warning by VC# 2005
Passing 'WAPS.Form1.listView1' as ref or out or taking its address may cause a runtime exception because it is a field of a marshal-by-reference class
after when i wrote these code :
private void Btn_Click(object sender, ClickEventArgs e)
{
Form1 ap = new Form1();
bool check = LS(ref ap.listView1, "abc");
ap.ShowDialog();
LG(ref ap.listView1, "abc", check);
}
bool LS(ref ListView lv, string contentSender)
{
}
void LG(ref ListView lv, string contentSender, bool iscontentfound)
{
}
i run the project and the code worked
but
anybody know why its coming or is it dangerous in future?
Becoming Programmer...
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MarshalByReference classes can live in a different or even on a different computer using .NET remoting, so it's not possible to get a reference to their members. In your case, Form1 will always be in the same AppDomain, so there shouldn't be any problems.
But why do you pass the ListView as reference? ListView already is a reference type, so you're actually passing a reference to a reference to a ListView, which is rarely useful.
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oh ok, i didnt know that listview is reference type
thanks so much
edited:
warning disappeared
thanks again
Becoming Programmer...
modified on Sunday, February 10, 2008 8:32
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Hi, I submitted an article on new C# XML processing package. Yet, it still has
not shown up as in the latest article section. When should I expect it to come
out?
Thanks,
jz
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Wrong forum. And you need to read before posting. It says it needs aproval, that can take a few days.
Edit: Even i havent found where it is. But still, they need manualy do it.
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same with me, i uploaded an article on 9th Jan, and it shown up around 8 Feb
Becoming Programmer...
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Wrong forum. You need to send an email to Chris.
"I guess it's what separates the professionals from the drag and drop, girly wirly, namby pamby, wishy washy, can't code for crap types." - Pete O'Hanlon
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I am using SQL 2005 with:
Dataset
BindingSource
TableAdapter
BindingNavigator.
And 5 Textboxes binded
I have overridden BindingNavigator Add and New icon to costum. Now after a change is done, how can i force a refresh without reopening?
And if i change text boxes, how can i make it permament change with simple databinding?
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How can i list all the virutal server which is on share point server(on remote computer)
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hi there,
i insert all the lines of textbox in a string array then run a for loop that checks entire array, if any error found then it will remove that string from array and set back array to textbox, like this :
string[] lines = textBox1.Lines;
for (int a = 0; a < lines.Length; a++)
{
if() //error found
lines[a] = null;
}
textBox1.Lines = lines;
but i have a problem that the errored lines becomes blank, thats why i want to put backspaces in those lines(errored lines) instead of null
but when i do that then there were boxes on errored lines
any idea to solve it?
thanks
Becoming Programmer...
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Hi,
you can't remove an item from an array; in an array with fixed length, the only thing you can do
is modify an item, but setting it to null does not *remove* it; when added to the textbox, it
will yield an empty line.
what you need is a collection (an ArrayList or a List< string> ) which behaves somewhat like
an array but does support item insertion/removal. So read up on ArrayList or List< T>.
ArrayList is easier for a novice but may need some casts, List< T> is a "generic" which exists
since C# 2.0
Luc Pattyn [Forum Guidelines] [My Articles]
This month's tips:
- before you ask a question here, search CodeProject, then Google;
- the quality and detail of your question reflects on the effectiveness of the help you are likely to get;
- use PRE tags to preserve formatting when showing multi-line code snippets.
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yeah i like ArrayList, but i dunno that why i didnt think about it before...xD
anyway thank you buddy
Becoming Programmer...
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Hello,
For strings you could allso use StringCollection[^] of System.Collections.Specialized namespace.
All the best,
Martin
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ArrayList worked but thanks for your helpful reply
Becoming Programmer...
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Hello friends,
I am a B.E student and have selected Visual C# as platform for my final year project.
You might be familiar with the Tab concept as in Tabbed Browser.
I want to implement the same concept in the file explorer. I mean I want to create a basic file explorer in windows which will have the GUI like "My Computer" and I want to provide the Tab facility in that. That means if I right click on drive C then I should get one option as "Open in new tab". And after clicking on this button I should have the contents of C drive opened in NEW TAB. So please help me in this as I am completely new to Visual C#. A complete code and running project is also welcome.  But at least tell me how to implement the explorer with basic file operations. Thank you in advance.
Koustubh Kulkarmi.
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kulkoustubh wrote: A complete code and running project is also welcome
Fat chance, you lazy little Indian. 
Didn't you read the forum guidelines related to homework assignments. I hope your tutor sees your post and throws you off your course. Then you can pursue a career that's more suited to your intellectual capabilities, like flippin' burgers in McDonalds. Here's their application form[^]. Good luck.
Paul Marfleet
"No, his mind is not for rent
To any God or government"
Tom Sawyer - Rush
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Who are you?
And by the way my platform is not Microsoft Technologies its my tutor because of whom i had to take project in Visual C#. Otherwise Microsoft Technologies  Suck. If i had taken the project i wanted then i would not need these forums and wouldn't have asked for your help. And you have no right to say anything about me. If you were a generous person you would have helped me. But since you are not an Indian you just cannot be generous. If you cant help me,don't interfere in my business. Get a life.
Koustubh Kulkarmi.
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