Re: Code & Compiler Efficiency - C# Discussion Boards

webhay24-Nov-05 8:35

24-Nov-05 8:35

Hello all,

i am using Datagrid to dispay row directly from my database but i need to click on one row to open details for this row from another table in the database where i can hang the value for the row with specifc row like in the combobox ValueMember

Thanks for help
Hoho

Re: DataGrid row value

Stanciu Vlad24-Nov-05 9:01

Stanciu Vlad

24-Nov-05 9:01

DataRowView currentRowInTheGrid = (DataRowView)this.dataGrid1.BindingManager[this.dataGrid1.DataSource, this.dataGrid1.DataMember].Current;

I hope you understand...because is a rough world out there...

Re: DataGrid row value

webhay24-Nov-05 9:24

webhay

24-Nov-05 9:24

Thanks so much about your help

but i need to know the ID of this current record to select the related details with this ID.

thank
hoho

Re: DataGrid row value

Stanciu Vlad24-Nov-05 9:29

Stanciu Vlad

24-Nov-05 9:29

Having the dataRowView you can obtain the coresponding dataRow :

DataRowView currentRowInTheGrid = (DataRowView)this.dataGrid1.BindingManager[this.dataGrid1.DataSource, this.dataGrid1.DataMember].Current;
DataRow currentRow = currentRowInTheGrid.Row;

object myId = currentRow["myIdColumnName"]; // is the same as object myId = currentRowInTheGrid["myIdColumnName"];

I hope you understand...because is a rough world out there...

Formatting Console.WriteLine

budidharma24-Nov-05 8:03

budidharma

24-Nov-05 8:03

Alright, I'm writing a bunch of integers to the screen of different lengths, followed by other numbers.

Some are 3 digits long, some are five digits long, and the maximum is about 6 digits long.
If the number is less than 6 digits long, I want it to write extra spaces after the number, to make it 6 total characters, before displaying more data.

Etc.

How do I do this?
Thanks, As Always.

Re: Formatting Console.WriteLine

Curtis Schlak.24-Nov-05 13:57

Curtis Schlak.

24-Nov-05 13:57

You should take a look at the Composite Formatting article on MSDN. It shows you the ins and outs of the process.

For your immediate satisfaction, though, try this:

String.Format( "{0,-6} {1,-6} {2,-6}", 7, 3.14, 0.5 );

"we must lose precision to make significant statements about complex systems."
-deKorvin on uncertainty

-- modified at 19:58 Thursday 24th November, 2005

Code & Compiler Efficiency

Andrew day24-Nov-05 7:28

Andrew day

24-Nov-05 7:28

I have 1 quick question

Example:

if(!Page.IsPostBack)
{
}

OR

if(Page.IsPostBack == True)
{
}

does the compiler treat the above statments the same, or is one more efficient then the other, cpu cycles etc....

Re: Code & Compiler Efficiency

Colin Angus Mackay24-Nov-05 8:03

Colin Angus Mackay

24-Nov-05 8:03

They are different, not because of the way that you've written them, but because the logic is different.

The first example, in pseudo code, says
IF PAGE IS NOT POSTBACK

While the second example, in pseudo code, says
IF PAGE IS POSTBACK

I wrote a wee program that tested both in release mode to see what the generated IL was:

if (isBlah)
{
	Console.Write("It is Blah");
}

became:

// Code Size: 14 byte(s)
.maxstack 1
L_0000: ldarg.0 
L_0001: brfalse.s L_000d
L_0003: ldstr "It is Blah"
L_0008: call void [mscorlib]System.Console::Write(string)
L_000d: ret

And

if (isBlah == true)
{
	Console.Write("It is Blah");
}

became:

// Code Size: 14 byte(s)
.maxstack 1
L_0000: ldarg.0 
L_0001: brfalse.s L_000d
L_0003: ldstr "It is Blah"
L_0008: call void [mscorlib]System.Console::Write(string)
L_000d: ret

So, you can see they are exactly the same thing. Which ever that you use is entirely up to you. What ever you feel more comfortable with the compiler will still turn it in to the same code.

Does this help?

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

Re: Code &amp;amp; Compiler Efficiency

Colin Angus Mackay24-Nov-05 8:29

Colin Angus Mackay

24-Nov-05 8:29

I did another quick test to show
if(!isBlah) Vs. if (isBlah == false)

The result was code exactly the same length as before. So, even by adding in the ! (not) operator there is no performance difference.

So, it all comes down to what ever is most readable for you.

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

-- modified at 14:29 Thursday 24th November, 2005

Re: Code &amp; Compiler Efficiency

leppie24-Nov-05 20:16

leppie

24-Nov-05 20:16

The compiler applies a cheap optimization technique called constant folding. eg

x = a + 3 + b + 7;

Gets converted to

x = a + 10 + b;

(given an integer type)

^{xacc.ide-0.1 released! Download and screenshots}

HashTable Beginning Question

budidharma24-Nov-05 7:27

budidharma

24-Nov-05 7:27

This is my first time working with hashtables. Here's what I'm trying to do, and what I need to do.

First, I have a HashTable that's initialized with the capacity of 169 (the number of possible pocket hands in holdem poker).

I deal two random cards to a player - and then create a string that looks like this, from the cards:
AKo, AKs, KKo, 32s ... etc. It'll always be in that format.

Now, I have a hashtable called HandCounter.

What I want to do, is check if that string exists as a "key" in the hash table. If it does, then get the value from that key and increment the value that is stored by 1. If it doesn't, then create a new key/value pair with the pocket string as the key and the int value 1.

Here's what I thought the code would probably look like:

if(HandCounter.ContainsKey(Hand.ToPocketString()))
{
HandCounter[Hand.ToPocketString()]++;
}
else
{
HandCounter.Add(Hand.ToPocketString(), 1);
}

Though something is wrong here. I'm attempting to use a string as the key, but it says it requires a type of "object" for the key. I'm attempting to use the value as an integer, but it says it uses type "object" as the value as well.

Do I need to typecast these?

Re: HashTable Beginning Question

budidharma24-Nov-05 7:40

budidharma

24-Nov-05 7:40

I just got this to work.

How do I enumerate through it, displaying the Key Value pairs?

Re: HashTable Beginning Question

budidharma24-Nov-05 7:45

budidharma

24-Nov-05 7:45

Alright, i just figured that out as well:
foreach(string Key in HandCounter.keys)
Console.WriteLine(Key + ": " + HandCounter[Key].ToString());

Very simple, jeez.

access controls in form1 from form2

Sam 200624-Nov-05 6:52

Sam 2006

24-Nov-05 6:52

i've searched these forums and google for this, ive found lots of questions about this, but no answers that worked for me. it would help if i could have an exact answer, because nothing ive found has helped me.

i have form1, when an item on a menu is clicked this code is called:

namespace.sendmessageform messageform = new namespace.sendmessageform();
messageform.ShowDialog();

the new form opens. when the form closes i need it to call a function on form1, how can i do this?

thanks in advance,
sam kline

-- modified at 12:52 Thursday 24th November, 2005

Re: access controls in form1 from form2

Robert Rohde24-Nov-05 7:08

Robert Rohde

24-Nov-05 7:08

messageform will need a reference to form1 so you should either pass form into the constructor of sendmessageform or give sendmessageform a property where you can set form1:

public class sendmessageform : Form {

private form1 _otherForm;

//Default constructor - should already exist
public sendmessageform() {
...
}

//new constructor to pass your reference
public sendmessageform(form1 otherForm) : this() {
_otherForm = otherForm;
}

//alternatively also create a property
public form1 OtherForm{
get { return _otherForm; }
set { _otherForm = value; }
}

//now you can call any function of form1 wherever you want
}

your code should then like either like

namespace.sendmessageform messageform = new namespace.sendmessageform(this);
messageform.ShowDialog();

namespace.sendmessageform messageform = new namespace.sendmessageform();
messageform.OtherForm = this;
messageform.ShowDialog();

Re: access controls in form1 from form2

Sam 200624-Nov-05 7:34

Sam 2006

24-Nov-05 7:34

it worked!
thanks a lot, you really helped me!

sam kline

Re: access controls in form1 from form2

Curtis Schlak.24-Nov-05 14:16

Curtis Schlak.

24-Nov-05 14:16

I would like to provide an alternate point of view, if you don't mind. You don't have to call the method from messagefom. The ShowDialog method blocks the main thread until it returns. If you need to call the same function every time, then you could do something like this:

namespace.sendmessageform messageform = new namespace.sendmessageform();
messageform.ShowDialog();
this.callTheFunctionYouNeedToCall();

If you have more than one function that can get called, you could define a property in your sedmessageform that your main form can access to decide what to do next. For example,

namespace.sendmessageform messageform = new namespace.sendmessageform();
messageform.ShowDialog();
switch( messageform.SomeProperty )
{
  case SomeEnum.Case1:
    // Do something here.
    break;
  case SomeEnum.Case2:
    // Do something here.
    break;
}

This design is more loosely coupled and does not require that your sendmessageform know about your main form. That would allow for better code re-use if you would like to use your sendmessageform again in another application or in another place in the same application.

I hope that helps you in some way.

"we must lose precision to make significant statements about complex systems."
-deKorvin on uncertainty

Re: access controls in form1 from form2

Sam 200624-Nov-05 17:36

Sam 2006

24-Nov-05 17:36

i never knew that it blocked the main thread, it will definately help me some time. thanks for the tip.

sam kline

Reflection, Breakpoints and Debug Mode Assembllies

Tristan Rhodes24-Nov-05 5:58

Tristan Rhodes

24-Nov-05 5:58

I have a question.

I have an assembly built in debug mode that I want to explore.

I wish to explore this assembly through Reflection, and at the break points, suspend execution and have a look around.

This can be done in VS.net, which is obviously well plugged into the CLR, but this has to also be possible outside the enviroment. Can this be done on code called by Reflection? Now i'm guessing that the whole breakpoint system is already built on reflection, so how is this done?

Cheers

Cata

Re: Reflection, Breakpoints and Debug Mode Assembllies

leppie24-Nov-05 11:00

leppie

24-Nov-05 11:00

You need a debugger. It has nothing to do with reflection.

^{xacc.ide-0.1 released! Download and screenshots}

Problem with events

sciamachy24-Nov-05 5:48

sciamachy

24-Nov-05 5:48

Hello,

I'm having a problem with events, I did some tutorials and I guess I understand how to use them, but I can't get this piece of code to work...
I get a NullPointReference Exception :

......<br />
<br />
<br />
public delegate void MovementEventHandler();<br />
<br />
/// <summary><br />
/// Summary description for Beagle.<br />
/// </summary><br />
public class Beagle<br />
{<br />
	private int x;<br />
	private int y;<br />
	public bool uptodate;<br />
<br />
	public event MovementEventHandler Movement;<br />
<br />
	public Beagle()<br />
	{<br />
		new Beagle(0,0);<br />
	}<br />
<br />
	public Beagle(int x, int y){<br />
<br />
<br />
		this.x = x;<br />
		this.y = y;<br />
<br />
		// Update world<br />
		Movement();<br />
	}<br />
....<br />
}

Tnx in advance !

-- modified at 11:49 Thursday 24th November, 2005

Re: Problem with events

Leslie Sanford24-Nov-05 6:58

Leslie Sanford

24-Nov-05 6:58

sciamachy wrote:

public Beagle()
{
new Beagle(0,0);
}

Hmm, this allocates a new instance of the Beagle class without assigning it to anything. Unless this is a construct new to C# v2.0 that I'm not aware of, I don't think you're accomplishing anything. Someone help me out here, if I'm wrong.

To initialize your fields, you can do this:

public Beagle()
{
    this.x = 0;
    this.y = 0;
    this.uptodate = true;
}

sciamachy wrote:
// Update world
Movement();

Oops! You're raising the event without checking to see if it is null. If no one has yet subscribed to the event when you attempt to raise it, you'll get a null exception.

Better to do something like this:

protected virtual void OnMovement()
{
    MovementEventHandler handler = Movement;

    if(handler != null)
    {
        handler();
    }
}

And call this method from elsewhere in your class when you need to raise the event.

TreeView question.

zaboboa24-Nov-05 4:26

zaboboa

24-Nov-05 4:26

Hello,

Is there a way of passing a dataset, or something like that, to populate a treeview, and not add a node at a time. And how to indicate in the dataset, or array the node hierarchy?

Thank you.

Re: TreeView question.

Robert Rohde24-Nov-05 4:39

Robert Rohde

24-Nov-05 4:39

Searching CodeProject sometimes gives valuable hits[^]

Method parameters

1nsp1r3d24-Nov-05 3:15

1nsp1r3d

24-Nov-05 3:15

Hi all,

As I was reading C# Language Pocket Reference, it says that all parameters are passed by value(ASAIK the book targets .NET 1.0). I thought that all reference types were passed by reference and all value types by value(enums and ints/floats/etc)? Is that the case?

Thanks,
gamehack

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