C# Discussion Boards - CodeProject

convert an expresion in a result

15-Apr-07 6:20

Hi,

I would say you cant set priority for the normal timer events:

all Windows.Forms.Timers get their event handled by the UI thread, hence at the same priority; it is unclear (I guess unspecified) in which order they would fire assuming
more than one of the timers is supposed to fire at a specific point in time
(maybe you will find my timers article interesting, it tells you more about the
resolution of the timer classes).

all other timers (Windows.Threading.Timer and Windows.Timers.Timer), as well as other
asynchronous events, typically use their own thread to service the event.
Here too, you typically dont control the thread's priority,
and the order of concurrent events is unspecified.

of course, you could organize a periodic event at a higher priority by using
your own thread, set at higher (maybe real-time) priority, and using a high-precision
timer (again see my article).

Hope this helps.

Smile | :)

Luc Pattyn

[My Articles]

xtremetechnology15-Apr-07 3:17

xtremetechnology

15-Apr-07 3:17

i have in a textbox "1+2+3". How can i convert this string to find the result aka 6 ?

Jun Du15-Apr-07 5:19

Jun Du

15-Apr-07 5:19

"1+2+3" from the textbox is just a string. How to interpret it is entirely up to you. So, in order to obtain the result, you need to write your own parsing rules and calculating logic.

Best,
Jun

xtremetechnology15-Apr-07 5:38

xtremetechnology

15-Apr-07 5:38

ok! But how could i interpret "+" like + operator ?
I am thinking to split the string "1+2+3", 1,2 and 3 are numbers, integer, but "+" what type it is?

Jun Du15-Apr-07 6:12

Jun Du

15-Apr-07 6:12

That type of string can be split to two categories: operands and operators. Operands are simply numbers. With operators, you cast them one by one. Pseudo code may be like this:

//...
switch(operator1)
{
case "+":
  result = operand1+operand2;
  break;
case "-":
  result = operand1-operand2;
  break;
//...
}

I am not aware of any shortcuts in this regard.

Best,
Jun

Jaiprakash M Bankolli15-Apr-07 7:39

Jaiprakash M Bankolli

15-Apr-07 7:39

First you need to split "+" into an array

Then each of the array value needs to be converted or Parsed and added

Regards,
Jaiprakash M Bankolli
jaiprakash.bankolli@gmail.com
http://jaiprakash.blog.com/

Leslie Sanford15-Apr-07 7:59

Leslie Sanford

15-Apr-07 7:59

You'll need to parse the strings into tokens and go from there. One approach is to use a recursive decent parser[^].

Moving list view items up or down.

sherifffruitfly15-Apr-07 15:09

sherifffruitfly

15-Apr-07 15:09

Google "lex yacc".

kripzz15-Apr-07 2:24

15-Apr-07 2:24

This is probably very simple but im having trouble getting my head around it.

Ive tried making a temporary list view item which stores the selected list view item,
Then move the selected list view item + 1 up one,
Then the selected list view item + 1 = the temporary,
But i keep getting errors.

Can anyone help me?

Luc Pattyn15-Apr-07 6:00

15-Apr-07 6:00

Hi, what is the View (LargeIcon, Details, ...) ?I have some experience with setting
icon positions on the desktop, which is a listview with View=LargeIcon.

Smile | :)

Luc Pattyn

[My Articles]

kripzz15-Apr-07 12:47

15-Apr-07 12:47

Details

Jaiprakash M Bankolli15-Apr-07 7:41

Jaiprakash M Bankolli

15-Apr-07 7:41

Can you send me your code so that we can pin point the error !!

Regards,
Jaiprakash M Bankolli
jaiprakash.bankolli@gmail.com
http://jaiprakash.blog.com/

kripzz15-Apr-07 13:07

Re: Moving list view items up or down. [modified]

15-Apr-07 13:07

Here is my code, im not sure if im even tackling this problem correctly.

<br />
        private void listView1_KeyDown(object sender, KeyEventArgs e)<br />
        {<br />
            if (e.KeyValue == 40)<br />
            {<br />
                ListViewItem temp = new ListViewItem();<br />
                ListViewItem temp2 = new ListViewItem();<br />
                for (int i = 0; i < listView1.SelectedIndices.Count; i++)<br />
                {<br />
                    if(listView1.SelectedItems[i].Index + 1 <= listView1.Items.Count)<br />
                    {<br />
                        //store next item in list<br />
                        temp = listView1.Items[listView1.SelectedItems[i].Index + 1];<br />
                        //store currently selected item<br />
                        temp2 = listView1.Items[listView1.SelectedItems[i].Index];<br />
<br />
                        //swap positions<br />
                        listView1.Items[listView1.SelectedItems[i].Index + 1] = temp2;<br />
                        listView1.Items[listView1.SelectedItems[i].Index] = temp;<br />
                    }<br />
                }<br />
            }<br />
        }<br />

Luc Pattyn15-Apr-07 13:38

15-Apr-07 13:38

Hi,

there is a bug: if the last listview item is selected (the one with index=count-1),
then temp will refer to the one with index=count, which exceeds the array.

there probably is a second bug: if items 2 and 3 are selected, then maybe
first 2 and 3 get swapped, then 3 and 4 get swapped, which might not be what
was intended.

index       0 1 2 3 4 5
So original A B C D E F
becomes     A B D C E F
then        A B D E C F

Also I am not sure the items in SelectedItems are in numerical
order, in selection order, or random order.

Furthermore, there is no need to create new ListViewItems (temp, temp2).

Hope this helps

Smile | :)

-- modified at 3:39 Monday 16th April, 2007

Luc Pattyn

[My Articles]

kripzz16-Apr-07 2:51

16-Apr-07 2:51

Im really stuck Frown | :(

Luc Pattyn16-Apr-07 3:08