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hey Friends....

I have a Table with Name (Student_Table)
fields(Stdid, StdRollNo, StuName)
with 5 records

And A windows Form With Name Form1

Now, My question is..
I want Dynamic Buttons equals to students records ie.. 5 buttons,
on That Buttons i want Student Roll No.

please guys help me

Jack_Spero

your question has been answered in the other forum you asked it in - a friendly bit of advice - please dont cross post - pick the best forum, post the question once !

'g'

Hello
I have been trying to export a string array from my C# unmanged DLL export to metatrader , but can not do that , please need you expert suggestion ..

[DllExport("_CheckStringArray", CallingConvention = CallingConvention.StdCall)]
        public static void _CheckStringArray([In, Out, MarshalAs(UnmanagedType.LPStr)]              StringBuilder []  str)
        {
         try
            {
                str[0].Append("hello");
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
        }

C#

#import "CyboMySqlRead.dll"
   void  _CheckStringArray(string  s[]);

   //-- import end

   string array [3] ;

   //-- calling dll method , should update first index with "hello"
    _CheckStringArray(array)

   Print(array[0]);  // nothing is printed here...

Is there a shorthand for updating an object? Something like an initializer?

C#

var item = new FooViewModel { id = "test", name = "test" };

Something like that but instead:

C#

Record myRecord = Context.RecordRepository.GetById(1234);

myRecord {
id = 123,
name = "blah"
}

Cheers, --EA

No, there isn't.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

The best you can do is try and using LINQ to fetch and update records in the same line.

However, what you are tyring to do is not directly possible.

Apps - Color Analyzer | Arctic | XKCD | Sound Meter | Speed Dial

In VB.net its called "WITH"
C# dont have this trick... But, you can use this:

/// <summary>
/// C# implementation of Visual Basics With statement
/// </summary>
public static void With<T>(this T _object, Action<T> _action)
{
    _action(_object);
}

Usage:

LongInstanceOfPersonVariableName.With(x => {
     x.AgeIntVar = 21;
     x.NameStrVar = "John";
     x.NameStrVar += " Smith";
     //etc..
});

from http://stackoverflow.com/a/5964848[^]
I dont think its the best solution... But... It may work.

modified 24-Jul-13 7:36am.

I have C# MDI Form EXE as a framework. In which I have to deployed my VB 6 OCX, and also calls another VB 6 OCX from displayed OCX events.

Is this possbile? where I have to make changes C# or VB 6.0?
Does anyone has made similar kind of project before?

Any link?

Thanks in Advance

It's just a COM component. You just add a reference to it and use it like any other class.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

Thanks Dave,

fisrt COM component loaded fine in C#.net exe framework. My problem is to load another COM component into same C#.net exe framework, and this second COM component will be called from first COM component.

Hope you understand my problem.

Any idea?

Exactly the same as before. You add a reference to it.

You're problem is that your COM componets should not be calling into each other. That would be a hard-code tie where you couldn't use one component without the other. That's just a bad design.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

I need to use a generic collection of keyvalue pair. I need thr folloeing:

1) should be generic because my values are a customized class
2) iterating should keep the order in which I added Items
3) I should be able to find the index of the element
4) I need access via Key

A dictionary is ok for 1,2,4 but not for 3
SortedList and SortedDictionary are ok for 1, 3, 4 but not for 2.
If I create a

C#

List<keyvaluepair>

it is ok for 1,2,3 but not for 4 ( I mean not directly)

C#

//Dictionary<string, double> d = new Dictionary<string, double>();
SortedList<string, double> d = new SortedList<string, double>();
            d.Add("z", 1);
            d.Add("a", 2);
            d.Add("c", 3);
            d.Add("b", 4);

            foreach (KeyValuePair<string,double> k in d)
            {
                Console.WriteLine(k.Key + " " + k.Value);
            }

// output: a 2  b 4 c 3 z 1
// but i need to preserve the order in whicth I added.
// I need output: z 1 a 2 c 3 b 4
// using Dictionary I preserve the order but how can select item using an index?

KeyValuePair<string, double> i_item = d.ElementAt(2); // if d is a Dictionary it is not possible

Any suggestion?
Thanks for your time

If I change your code to use a Dictionary it works for me... Confused | :confused:

If you directly want to access a value you can also do this:

C#

var value = d["c"];

whil returns the value 3 in this case.

What error do you get when using the Dictionary class?

KeyValuePair<string, double> i_item = d.ElementAt(2); // if d is a Dictionary it is not possible

may be I was not clear I can't get item from index value. For example I need the second element How can I ask the Dictionary the second element?
The dictionary is an unsorted collection

An unsorted collection is what you're looking for if you want to prevent the order in which the items were added.

And I don't know what error you're getting when calling

C#

KeyValuePair<string, double> i_item = d.ElementAt(2);

as this works just fine for me with a dictionary

thanks you are right sorry. Basically I need to find the index from the key and viceversa.

How can I find the index related to the key "3", from the dictionary. It should be 2

Why do you need to be able to get the index of a KeyValuePair if you already got the key? Confused | :confused:

Maybe take a look at the hint from Keith.

Note: As I just saw after a bit of researching, the Dictionary uses some hashing of the keys to create some order which means it does not necessarily return the items in the order in which they were added

Source: http://msdn.microsoft.com/en-us/library/xfhwa508.aspx[^]

Quote:
For purposes of enumeration, each item in the dictionary is treated as a KeyValuePair<tkey, tvalue=""> structure representing a value and its key. The order in which the items are returned is undefined.

Ordered Dictionary[^] has access via the index and the key. Looks promising.

PB 369,783 wrote:
I just find him very unlikeable, and I think the way he looks like a prettier version of his Mum is very disturbing.[^]

But its not Generic Laugh | :laugh:

Well one could create a Generic wrapper for it Wink | ;)

I'll get me coat.

PB 369,783 wrote:
I just find him very unlikeable, and I think the way he looks like a prettier version of his Mum is very disturbing.[^]

This article might help: OrderedDictionary<T>: A generic implementation of IOrderedDictionary[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

I really like (and upvoted) your question; it was fun to see what I could implement quickly, and I'm going to post the code here before I read the other responses on the thread, since I feel I can learn something from knowing whether or not the code I post actually meets your requirements, and, possibly, learning from other people's responses.

I wonder if I have not just duplicated the functionality of a Dictionary<K, V> ? Also, I suspect Linq queries could be used in some way, efficiently here, rather than, as I did, creating two Lists in the class (memory cost ?).

Disclaimer: I've tested only with KeyValuePair<string, double> since that's what you used. Testing with instances of a custom class as K, or V: that's on my list Smile | :)

Here's the revised class:

C#

public class IndexedKVPList<K, V> : List<KeyValuePair<K, V>>
{
    private readonly List<K> keyList = new List<K>();
    private readonly List<V> valueList = new List<V>();

    // modified to use 'new
    new public void Add(KeyValuePair<K, V> newKVP)
    {
        keyList.Add(newKVP.Key);
        valueList.Add(newKVP.Value);
        base.Add(newKVP);
    }

    // new function to Remove KeyValue pair
    new public void Remove(KeyValuePair<K, V> killKVP)
    {
        if(! this.Contains(killKVP)) throw new Exception("error in Remove in IndexedKVPPair");

        keyList.Remove(killKVP.Key);
        valueList.Remove(killKVP.Value);
        base.Remove(killKVP);
    }

    public KeyValuePair<K, V> GetKVPByValue(V theValue)
    {
        return this[valueList.IndexOf(theValue)];
    }

    public K GetKeyByValue(V theValue)
    {
        return this[valueList.IndexOf(theValue)].Key;
    }

    // new function to get the index by KeyValue pair
    public int GetIndexByKVP(KeyValuePair<K, V> theKVPPair)
    {
        return this.IndexOf(theKVPPair);
    }

    // new function to get the index by Value
    // what happens if there are multiple identical values ?
    public int GetIndexByValue(V theValue)
    {
        return (valueList.IndexOf(theValue));
    }

    public KeyValuePair<K, V> GetKVPByKey(K theKey)
    {
        return this[keyList.IndexOf(theKey)];
    }

    public V GetValueByKey(K theKey)
    {
        return this[keyList.IndexOf(theKey)].Value;
    }

    // new function to get the index by Key
    public int GetIndexByKey(K theKey)
    {
        return (keyList.IndexOf(theKey));
    }
}

Here's the revised test:

XML

private void TestIKVP()
{
    var iKVList = new IndexedKVPList<string, double>();

    for (int i = 0; i < 10; i++)
    {
        iKVList.Add(new KeyValuePair<string, double>("Key: " + i, i));
    }

    var kvp1 = iKVList.GetKVPByKey("Key: 8");
    var kvp2 = iKVList.GetKVPByValue(6);

    Console.WriteLine(kvp1 + " " + kvp2);

    // test Remove function
    iKVList.Remove(iKVList[4]);

    foreach (var theKVP in iKVList)
    {
        Console.WriteLine(theKVP.Key + " Value:" + theKVP.Value.GetType());
    }

    Console.WriteLine(iKVList.GetIndexByKVP(kvp2));
    Console.WriteLine(iKVList.GetIndexByKey("Key: 9"));
    Console.WriteLine(iKVList.GetIndexByValue(3));
}

~
“This isn't right; this isn't even wrong." Wolfgang Pauli, commenting on a physics paper submitted for a journal

modified 22-Jul-13 7:06am.

Thanks a lot, I did a workaround using a syncronized List..

Then I found the following solution

C#

Dictionary<string, double> d = new Dictionary<string, double>();

           d.Add("z", 1);
           d.Add("a", 2);
           d.Add("c", 3);
           d.Add("b", 4);

           foreach (KeyValuePair<string, double> k in d)
           {
               Console.WriteLine(k.Key + " " + k.Value);
           }



           KeyValuePair<string, double> i_item = d.ElementAt(2);

           int myIndex = Array.IndexOf(d.Keys.ToArray<string>(), "a");

It may be a little faster to get the index using:

private int theIndex;
//
theIndex = dictionaryStringInt.Keys.ToList<string>().IndexOf("KeyString");

However, note that in using both 'ElementAt, and 'ToArray ... or 'ToList ... you are using Linq functions that are, internally, going to do an enumeration.

If the entries in the dictionary are not being removed, moved around, etc., then you could create a List<keytype> once from the Keys collection, however, I doubt that's the case you want here.

I will add some extra functions that return an index to my first answer above, with the hope some of our members here who have more formal computer science training (than I do) will comment on the relative cost / lookup-times, of the example I've given.

good luck, Bill

~
“This isn't right; this isn't even wrong." Wolfgang Pauli, commenting on a physics paper submitted for a journal

thanks very useful