Re: struct and const - C# Discussion Boards

Colin Angus Mackay21-Jun-07 4:37

Colin Angus Mackay

21-Jun-07 4:37

I think you need to make it a static readonly.

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lune1221-Jun-07 5:01

lune12

21-Jun-07 5:01

Thanks, But:

If you do,
Public static readonly Point;
and after you try to do,
Point.x = 3;
you get an error, as Point is readonly and can't be assign.

So what is the right way...

Colin Angus Mackay21-Jun-07 8:05

Colin Angus Mackay

21-Jun-07 8:05

Point is immutable. You couldn't change it even if you wanted to.

public static readonly Point myPoint = new Point(3,5);

Luc Pattyn21-Jun-07 5:08

21-Jun-07 5:08

public static readonly Point p24=new Point(2, 4);

Smile | :)

Luc Pattyn

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PIEBALDconsult21-Jun-07 9:05

21-Jun-07 9:05

If your goal is to have a Point type, just use the built-in one: System.Drawing.Point.

If your goal is to create a type that works like System.Drawing.Point, then look at how System.Drawing.Point is defined.

If your goal is to create a type that works the way you described (which I don't recommend)...

public struct Point
{

// _z will hold two flag bits to hold whether or not the values have been set
private int _x,_y,_z;

public int
x
{
    get
    {
        if ( _z%2 == 1 )
        {
            return ( _x ) ;
        }
        else
        {
            // throw something
        }
    }

    set
    {
        if ( _z%2 == 0 )
        {
            _x = value ;
            _z |= 1 ;
        }
        else
        {
            // throw something
        }
    }
}

public int
y
{
    get
    {
        if ( _z > 1 )
        {
            return ( _y ) ;
        }
        else
        {
            // throw something
        }
    }

    set
    {
        if ( _z < 2 )
        {
            _y = value ;
            _z |= 2 ;
        }
        else
        {
            // throw something
        }
    }
}

Then

<br />
public Point my_Point;<br />
my_Point.x = 2;<br />
my_Point.y = 4;<br />
<br />
my_Point.x = 5; // The "throw something" will happen<br />

Luc Pattyn21-Jun-07 10:41

21-Jun-07 10:41

You almost convinced me to embrace nullable types...

Luc Pattyn

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PIEBALDconsult21-Jun-07 11:00

21-Jun-07 11:00

I didn't think to use nullable types until some time after I posted.
Thanks for reminding me, I'll get right on that.

Colin Angus Mackay21-Jun-07 14:07

Colin Angus Mackay

21-Jun-07 14:07

Luc Pattyn wrote:
You almost convinced me to embrace nullable types...

Nullable types are gooooodddd!!! Come and see the pretty nullable types.....

PIEBALDconsult21-Jun-07 14:51

21-Jun-07 14:51

"Use the right tool for the right job." -- Scotty... and my grandfather

Luc Pattyn21-Jun-07 14:54

21-Jun-07 14:54

Hi Colin,

I'm sure nullable types have some value (no pun intended), otherwise they
would not have been added to C#.

So far whenever I was short of a special value (such as DateTime.MinValue),
I used a class rather than a struct so I could use null to indicate "has no value".

I still have to encounter the first case I really can take advantage of a
nullable value; maybe a long history without them made me develop patterns
that just walk around them ?

Regards,

Luc Pattyn

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PIEBALDconsult21-Jun-07 11:09

Re: How to refresh a form

21-Jun-07 11:09

Same thing, but with nullable type -- still not recommended practice though.

public struct Point
{


private int? _x,_y;

public int
x
{
    get
    {
        if ( _x.HasValue )
        {
            return ( _x.Value ) ;
        }
        else
        {
            // throw something
        }
    }

    set
    {
        if ( !_x.HasValue )
        {
            _x = value ;
        }
        else
        {
            // throw something
        }
    }
}

public int
y
{
    get
    {
        if ( _y.HasValue )
        {
            return ( _y.Value ) ;
        }
        else
        {
            // throw something
        }
    }

    set
    {
        if ( !_y.HasValue )
        {
            _y = value ;
        }
        else
        {
            // throw something
        }
    }
}

How to refresh a form

kaushal65421-Jun-07 3:43

kaushal654

21-Jun-07 3:43

In my application I represent data stored in sql 2005 by "dundas" graphs. That data are dynamically updated. I want to refresh my graphs automatically.

Ylno21-Jun-07 14:30

Ylno

21-Jun-07 14:30

Hello,

I'm pretty new to all this so i hope i haven't picked up the wrong end of the stick..

If you want the form to re-paint it's self then you can use then following method :

.Invalidate()

That will cause the control to re-draw it's self.

how can we find a *.dmp in a directory in c#

cancerion21-Jun-07 3:40

cancerion

21-Jun-07 3:40

hello

can anyone help me

how can we find a *.dmp in a directory in c#???

thanks in advance

sachin

Re: how can we find a *.dmp in a directory in c#

Wjousts21-Jun-07 3:42

Wjousts

21-Jun-07 3:42

Directory.GetFiles(mypath,"*.dmp);

Re: how can we find a *.dmp in a directory in c#

Giorgi Dalakishvili21-Jun-07 4:00

Giorgi Dalakishvili

21-Jun-07 4:00

I guess you meant Directory.GetFiles(mypath,"*.dmp");

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Re: how can we find a *.dmp in a directory in c#

Wjousts21-Jun-07 6:54

Wjousts

21-Jun-07 6:54

how to add value and text in combo box in c# windows application

monuSaini21-Jun-07 2:45

monuSaini

21-Jun-07 2:45

Hello every body,

I want to add items in combo box (drop down style sets to DropdownList)

with text and values.

I am able to add only text not its value.

Please help,

Regards,

rahul saini

Re: how to add value and text in combo box in c# windows application

Luc Pattyn21-Jun-07 2:49