Re: Using dictionaries - C# Discussion Boards

19-Oct-09 3:00

I have used a dictionary before in the form of Dictionary<tkey, tvalue=""> but is it valid to use it like this, Dictionary(TKey, TValue, TValue), if not what is the best way to do this or a good alternative.

Thanks

Keith Barrow19-Oct-09 3:07

19-Oct-09 3:07

What you are asking for is syntactically illegal in a .net Dictionary.

Formally a dictionary key directly maps onto the value (but not necessarily the reverse), and only one instance of key can exist per dictionary.

What you need to do depends up what you are trying to acheive, if you give more information I might be able to provide more help.

CCC solved so far: 2 (including a Hard One!)

Paul Harsent19-Oct-09 3:14

19-Oct-09 3:14

I am reading in a txt file, and pulling out a drive name(string), start time (float), end time (float) and maybe a date in the future but not using that just yet. These will need to be stored. There will be more than one start and end time per drive. Once the data has been read in and stored I will need to then read the data back to make a graph out of the data.

Hope this is clear.

Thanks

Pete O'Hanlon19-Oct-09 3:16

Pete O'Hanlon

19-Oct-09 3:16

You can use more complex types in a Dictionary, so you could have a Dictionary<string, List<float, float>> here.

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Keith Barrow19-Oct-09 3:39

19-Oct-09 3:39

I think you need a class along the lines of

public class RetrievedTiming 
{
  public string Drive { get; set; }
  public DateTime Start { get; set; }
  public DateTime End { get; set; }
  // public string Filepath { get; set; } //Possibly - see post
}

How you store this depends upon whether you only get one timing per file or not. If there is only one timing per file , You could use Dictionary<string, RetrievedTiming> where the string is the filename.

If you have more than one timing per file the dictionary is no good, but you have a choice of either creating a class FileTimings which has the filename as a property and a List<RetrievedTiming> containing the timings from the file, or simply adding the commented Filepath property to the RetrievedTiming class and maintaining a list of this. [Edit] or, in line with Pete's Suggestion you could Have Dictionary<string, List<RetrievedTiming>> [/Edit]

Personally, I'd start with the last option (the List<RetrievedTiming> with the Filepath property)and develop around that (and replace it with the FileTimings based option if it becomes unweildy). One of the good things about the last option is that you can use LINQ to search the timings easily. See here[^] for a very brief introduction to using LINQ to search a list of objects(in this case an array, but it applies to generic lists too).

CCC solved so far: 2 (including a Hard One!)

Paul Harsent19-Oct-09 6:00

19-Oct-09 6:00

I have tried using Dictionary<string, list<float,="" float="">> = new Dictionary <string, list<float,="" float="">>(); but i get a compliation error

using the generic type 'System.Collections.Generic.List<t>' requires '1' type arguments

Any ideas.

Thanks

Keith Barrow19-Oct-09 6:16

19-Oct-09 6:16

The syntax in your post is screwed up,
if you want to display > you have to type & g t ; (without the spaces) and similar for < as Code Project renders like web page
I can't help until I get the correct code, but it sounds like you are not declaring the generic properly. You can see examples in the previous posts.

CCC solved so far: 2 (including a Hard One!)

Paul Harsent19-Oct-09 22:54

19-Oct-09 22:54

static Dictionary<string, List<float, float>> drive = new Dictionary<string, List<float, float>>();

this is the syntax im using.

Thanks for the help

Keith Barrow19-Oct-09 23:29

how to catch keydown event in datagridview

19-Oct-09 23:29

The nested generic syntax is very powerful, but ugly (but I think there is no rational way around that problem) so errors are often difficult to spot, especially if you haven't used them very much.

The problem in the code snippet is List<float,float> you can only have one generic type in a list (e.g.
List<float> If you want to store two floats this way, you need to create a class with two float properties (Like the example I posted yesterday) e.g.

public class Foo
{
  public float Value1 { get; set; }
  public float Value2 { get; set; }
}

public class Program
{
  public void Main()
  {
    Dictionary<string, List<Foo>> Bar = new Dictionary<string, List<Foo>>();
  }
}

I suggest you research both generics, and the various common collection types (e.g. List, Collection, Dictionary, Linked List, Hashtable, Set etc.). The .Net framework doesn't have all these (e.g. I've had to implement a Set type), but a grounding in each will let you know when to use it and will stand you in good sted in your career.

CCC solved so far: 2 (including a Hard One!)

han275419-Oct-09 2:31

han2754

19-Oct-09 2:31

I use C# express edition 2008,windows XP sp2.

if In rowheader a datagridview i keydown delete key,I want the row to be deleted.
but i cannot trap the keydown event,
my question is how to do that.

thank you
han

han

Re: how to catch keydown event in datagridview

Henry Minute19-Oct-09 4:20

Henry Minute

19-Oct-09 4:20

If you have the AllowUserToDelete property (that may not be the exact name but it is pretty close, I'm doing this from memory) set to true then Ctrl-Del should do what you want.

Hope that this helps. Smile | :)

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

Re: how to catch keydown event in datagridview

han275419-Oct-09 13:21

han2754

19-Oct-09 13:21

Hello Henry
thank you ,it work.

han Smile | :)

Check if MessageBox is on

tamir90119-Oct-09 1:04

tamir901

19-Oct-09 1:04

Hi,

I Build an application with timer that is checking every second (on_Tick event)
if the second eq to "00",
and if it's true a messagebox launch with some message.

My problem is - if the user dosen't press OK the message will show again at the next minute (when the second will eq to "00").

How can i launch the messagebox only if there isn't any othere nessagebox.

10x

Christian Graus19-Oct-09 1:07

Christian Graus

19-Oct-09 1:07

You'd have to either stop the timer until the message box has been shown, or you'd have to write your own message box class so you can set some sort of flag.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

tamir90119-Oct-09 1:16

tamir901

19-Oct-09 1:16

Christian Graus wrote:
you'd have to write your own message box class so you can set some sort of flag.

But if i'll stop the timer i don't think i can start it again,
can i?
and how i can check if the user press OK, with the Dialog Result?

Christian Graus wrote:
or you'd have to write your own message box class so you can set some sort of flag.

Can I overrite it?
can you please explain me have to do it?

Christian Graus19-Oct-09 1:44

Christian Graus

19-Oct-09 1:44

tamir901 wrote:
But if i'll stop the timer i don't think i can start it again,
can i?

Why not ?

tamir901 wrote:
and how i can check if the user press OK, with the Dialog Result?

A message box only has one button. So you show it, and the next line of code restarts the timer.

i think you need to buy a book, desperately.

tamir901 wrote:
can you please explain me have to do it?

You either stop the timer, or you write your own dialog box. If you don't know how to create a form, you REALLY need to buy a book. The point is that your dialog box would include a flag, which is set to true while the form is visible, or you could just show and hide a static instance and check if it's visible directly.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.