C# Discussion Boards - CodeProject

6-Jun-07 4:18

Hi guys,
I need some help please, I have a treeview and for each node I want to show tooltip data; this data is stored in a table and I don't think querying the table everytime the mouse is moved is a good idea. I was wondering if anybody knew a different way of showing the tooltip with database table data.

Please help!!!

sasa

I Believe In GOD6-Jun-07 4:30

I Believe In GOD

6-Jun-07 4:30

hi

when you building your treeview
try to store your tooltip in ArrayList

then query the tooltip from this ArrayList

Have a good day ....

I know nothing , I know nothing

Saamir6-Jun-07 4:34

6-Jun-07 4:34

Thank you for your response. I have never used an arraylist before I googled and found some information but none shows on how to query an arraylist. Could you please give me an example.

sasa

Giorgi Dalakishvili6-Jun-07 4:31

Giorgi Dalakishvili

6-Jun-07 4:31

Query the table just once when the treeview is loaded and store it in a datatable. After that display the data when the mouse is moved.

my articles

Saamir6-Jun-07 4:44

6-Jun-07 4:44

Thank you for your response. I believe I know how to do this. Either way once I have the datatable in order to get the tooltip data for that particular node, do I use datarow.select based on the ID of the data that I want to show?

Please advice

sasa

Saamir6-Jun-07 4:54

6-Jun-07 4:54

Thanks buddy. I got it to work with your suggestion.

sasa

Re: Connection with Oracle9i

Giorgi Dalakishvili6-Jun-07 5:09

Giorgi Dalakishvili

6-Jun-07 5:09

You are welcome Smile | :)

my articles

Connection with Oracle9i

sarwarmdgolam6-Jun-07 4:16

sarwarmdgolam

6-Jun-07 4:16

I faced a problem when connting wiht Oracle9i. Plz somebody give me the instruction.
How can i get connected with Oracle9i.

sarwarmdgolam

Tarakeshwar Reddy6-Jun-07 5:17

Tarakeshwar Reddy

6-Jun-07 5:17

What kind of problem are you facing?

Using enumerated types

Dewald6-Jun-07 3:56

6-Jun-07 3:56

OK, this is probably the C++ programmer in me still trying to break through the C# fog (so far it's been quite a pleasant learning curve though).

I woud like to "give names" to the values that my functions return. In my C++ days I would have used something like

#define OK                0<br />
#define ERR_PORT_NOT_OPEN -100<br />
#define ERR_NO_CARRIER    -101

etc.

A function can then return ERR_PORT_NOT_OPEN if the port is not open as opposed to a meaningless int value of -100.

So I thought I'd go with enumerated types in C# and while it works I do feel that it could be a little more elegant.

I wrote a class called Defines with an enumerated type resembling this:

public enum ERR<br />
{<br />
   OK = 0,<br />
   PORT_NOT_OPEN = -100,<br />
   NO_CARRIER = -101,<br />
}

so now a function can return Defines.ERR.PORT_NOT_OPEN as opposed to -100.

My gripe with this approach is that I'm constantly having to typecast this enumerated type to (int). In other words the function has to return (int)Defines.ERR.PORT_NOT_OPEN and if I want to compare the outcome of a function with a switch for instance I have to do something like:

switch (myFunc())<br />
{<br />
   case (int)Defines.ERR.PORT_NOT_OPEN:<br />
      ...<br />
      break;<br />
   case (int)Defines.ERR.NO_CARRIER:<br />
      ...<br />
      break;<br />
}

I don't want to change the return type of the functions from int to Defines.ERR because I still have to use native functions which return int values (corresponding to the #define values of course).

So what do you guys do to achieve what I'm trying to?

DavidNohejl6-Jun-07 4:05

DavidNohejl

6-Jun-07 4:05

Dewald wrote:
#define OK 0
#define ERR_PORT_NOT_OPEN -100
#define ERR_NO_CARRIER -101

static class ErrCodes
{
const int ERR_PORT_NOT_OPEN = -100;
const int ERR_NO_CARRIER -101;
...
}

"Throughout human history, we have been dependent on machines to survive. Fate, it seems, is not without a sense of irony. " - Morpheus
"Real men use mspaint for writing code and notepad for designing graphics." - Anna-Jayne Metcalfe

Dewald6-Jun-07 4:57

6-Jun-07 4:57

Thanks dnh, this looks great. Do you have any idea what the implications on memory usage is of this approach? The whole reason why, in C++ #defines were used is to save the memory that would have been allocated had the defines been constants or variables.

Guffa6-Jun-07 4:10

Guffa

6-Jun-07 4:10

Dewald wrote:
I don't want to change the return type of the functions from int to Defines.ERR

This is your problem. As long as you want to use an int value, the coding will be somewhat painful.

If you want to avoid writing (int) here and there, you can create constants instead of using an enum. That would work pretty much as using #define in C++.

---
single minded; short sighted; long gone;

Dewald6-Jun-07 4:49

6-Jun-07 4:49

Thanks Guffa,

The reason I steered away from constants is because that would take up memory. I know memory conservation is probably not a big deal nowadays but I still tend to cringe when unneccesary memory is being taken up.

Dave Kreskowiak6-Jun-07 5:06

Dave Kreskowiak

6-Jun-07 5:06

Constants are only stored once, like a static. If you have a constant defined in a class and multiple objects created from that class, the runtime won't create multiple copies of the same constants. There will only be one copy of the constants in memory usable by every instance of the class.

In a world where a machine comes with 128M minumum, a few constants, or a few hundred constants, are not going to break the bank. An int32 constant is just 4 bytes. Even if you have 1,000 constants in a class and a thousand objects created from that class, you're still only using 4K for the constants.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

Guffa6-Jun-07 9:05

Guffa

6-Jun-07 9:05

Dave Kreskowiak wrote:
Constants are only stored once, like a static.

That is only true for reference type constants. Value type constants, like in this case, isn't stored anywhere. They are inlined in the code that uses it, producing the same code as if a literal value had been used.

Dave Kreskowiak wrote:
Even if you have 1,000 constants in a class and a thousand objects created from that class, you're still only using 4K for the constants.

Nope. Zero bytes.

---
single minded; short sighted; long gone;

Dewald6-Jun-07 20:50

6-Jun-07 20:50

Thanks guys,

That's very interesting and really god to know.

Guffa6-Jun-07 8:59

Guffa

6-Jun-07 8:59

Dewald wrote:

The reason I steered away from constants is because that would take up memory.

No, they don't. Constants are inlined at compile time, so they don't take up more memory than literal values.

I prefer using an enum rather than constants in a case like this, as an enum says a lot more about what a method returns than an int does. When a method returns an enum value, you don't have to read a lot of documentation to find out what constants to use to compare the return value with.

If you want the int value you can easily cast the enum to int, and use that with any existing code that requires an int.

---
single minded; short sighted; long gone;