CODEWITHSUNDEEP
c#
Mohammad
Mohammad

Reputation: 2764

Array of objects with custom index

I have these two classes:

public class Message
{
    string Message;
    string Code;
}

public class MessageInitializer
{
    DataSet ds;
    DataRow dr;
    message[] ms;
}

I want to create a constructor in MessageInitializer like this:

MessageInitializer()
{
    this.ms = new Message[ds.Tables[0].Rows.Count];
    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
    {
        dr = ds.Tables[0].Rows[i];
        ms[(string)dr.ItemArray[0]] = (string)dr.ItemArray[1];
    }
}

But array's index must be int type. I have no idea how to work this out:

ms[(string)dr.ItemArray[0]] = (string)dr.ItemArray[1];

Update:

Code format is a string like this: [001-001-001], so I can't convert it to integer.

Upvotes: 6

Views: 3532

Answers (4)

Nikolai Samteladze
Nikolai Samteladze

Reputation: 7797

If you just want to get a list of all the messages from the database, then you can use the code below. Note, List instead of Array. Easier to use and faster.

public class Message
{
    string Message;
    string Code;
}

public class MessageInitializer
{
    DataSet ds;
    DataRow dr;
    List<Message> ms;

    MessageInitializer()
    {
        this.ms = new List<Message>();
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            dr = ds.Tables[0].Rows[i];
            ms.Add(new Message
            {
                 Code = dr.ItemArray[0].ToString(),
                 Message = dr.ItemArray[1].ToString(),
            });
        }
    }
}

You mentioned that you have couple million records. List will perform fine in case you want to access items sequestially. If you want to access items in a non-sequential manner, I suggest you use Dictionary instead (to improve search perfromance):

public class MessageInitializer
{
    DataSet ds;
    DataRow dr;
    Dictionary<string, Message> ms;

    MessageInitializer()
    {
        this.ms = new Dictionary<string, Message>();
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            dr = ds.Tables[0].Rows[i];
            ms.Add(dr.ItemArray[0].ToString(), new Message
            {
                 Code = dr.ItemArray[0].ToString(),
                 Message = dr.ItemArray[1].ToString(),
            });
        }
    }
}

You can access message as follows:

var message = ms["001-001-001"];

It will be orders or magnitude faster than accessing a random List item:

var message - ms.First(x => x.Code == "001-001-001");

Upvotes: 3

Mohammad Chamanpara
Mohammad Chamanpara

Reputation: 2159

you don't need Message class any more. Using a dictionary as follows solves the problem :

public class MessageInitializer
{
    DataSet ds;
    DataRow dr;
    Dictionary<string, string> ms;
    public MessageInitializer()
    {
        this.ms = new Dictionary<string,string>(ds.Tables[0].Rows.Count);
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            dr = ds.Tables[0].Rows[i];
            ms[(string)dr.ItemArray[0]] = (string)dr.ItemArray[1];
        }
    }
}

I hope this would be helpful.

Upvotes: 5

Yoan Pumar
Yoan Pumar

Reputation: 94

I think what you want to perform is the following:

public class Message
{
    public string message { get; set; }
    public string code { get; set; }

}

public class MessageInitializer
{
    DataSet ds;
    DataRow dr;
    Message[] ms;

    MessageInitializer()
    {
        this.ms = new Message[ds.Tables[0].Rows.Count];
        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        {
            dr = ds.Tables[0].Rows[i];
            ms[i] = new Message
            {
                code = (string)dr.ItemArray[0],
                message = (string)dr.ItemArray[1]
            };
        }
    }
}

Upvotes: 1

A G
A G

Reputation: 22559

I think you just want build an array of messages from ds.Tables[0]

Code -
ms[i].Code = (string)dr.ItemArray[0];

Message -
ms[i].Message = (string)dr.ItemArray[1];

MessageInitializer()
{
    this.ms = new Message[ds.Tables[0].Rows.Count];
    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
    {
        dr = ds.Tables[0].Rows[i];
        ms[i].Code= (string)dr.ItemArray[0];
        ms[i].Message = (string)dr.ItemArray[1];
    }
}

For better performance make use of Parallel.ForEach - 

Parallel.ForEach(ds.Tables[0].AsEnumerable(), row => {
        ms[i].Code= (string)row.ItemArray[0];
        ms[i].Message = (string)row.ItemArray[1];
});

Upvotes: 3

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