Getting the value of index of list c#

Question

1.00/5 (1 vote)

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Hi. How is it possible to get the value of a certain index in a List<>.
I use Join when I have 1D list/array. But i Cannot use it for multidimensional, here's what Im trying to do

C#

protected void lnkStep3(object sender, EventArgs e)
   {
       List<OrderFields> listOrderBy = OrderBy();
       string strOrderByFields = "";
       for (int i = 0; i <= listOrderBy.Count - 1; i++)
       {
           strOrderByFields += listOrderBy[i][0];
       }
     
      
   }

public List<OrderFields> OrderBy()
    {
        List<OrderFields> listOrderBy = new List<OrderFields>();
        for (int i = 0; i <= gvFilters.Rows.Count - 1; i++)
        {
            TextBox txtOrder = (TextBox)gvFilters.Rows[i].FindControl("txtOrder");
            DropDownList drpTableName = (DropDownList)gvFilters.Rows[i].FindControl("drpTableName");
            DropDownList drpFieldName = (DropDownList)gvFilters.Rows[i].FindControl("drpFieldName");
            string ordervalue = drpTableName.SelectedValue.ToString() + "." + drpFieldName.SelectedValue.ToString();
            listOrderBy.Add(new OrderFields(Convert.ToInt32(txtOrder.Text), ordervalue));
        }
        listOrderBy.Sort(delegate(OrderFields x, OrderFields y)
        {
            return x.OrderNo.CompareTo(y.OrderNo);
        });
        return listOrderBy;
    }

What I have tried:

I am trying to concatenate the values of index[1] of strOrderByFields List with comma

Posted 15-Feb-16 16:07pm

bjay tiamsic

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Comments

Sergey Alexandrovich Kryukov 15-Feb-16 22:34pm

There is no such thing as "multidimensional list". What many call a "multidimensional array" does exist, but, more correctly, this is an "array of rank N". The value of the list is taken by index using the operator []. Your problem in unclear and probably does not even exist; it's just the problem of your understanding. You may have a chance to get help if you explain what do you want to achieve, ultimately.
—SA

bjay tiamsic 16-Feb-16 0:30am

I got this class.

public class OrderFields
{
public int OrderNo { get; set; }
public string OrderField { get; set; }

public OrderFields(int num, string field)
{
OrderNo = num;
OrderField = field;
}
}

I added items to it using the codes in my main post and I want to get the values of OrderField

Sinisa Hajnal 16-Feb-16 2:52am

Then you take the element of the List that contains OrderField (which is by the way an object and even if you list <orderfield> was an array it would be single dimension). See the solution below.

bjay tiamsic 16-Feb-16 0:32am

What to you call this by the way? List with 2 values like a 2D Array?

Sergey Alexandrovich Kryukov 16-Feb-16 1:01am

List with two values is not even like "2D Array", it's a list with 2 elements. I cannot understand where your confusion comes from, but it looks like a big confusion...
—SA

bjay tiamsic 16-Feb-16 18:58pm

Sorry I'm really not familiar with this but I think it's getting clearer

Sergey Alexandrovich Kryukov 16-Feb-16 20:31pm

Please understand that arrays and collections are among the fundamentals you cannot afford to miss; it's impossible to do any real programming without them.
—SA

bjay tiamsic 16-Feb-16 20:37pm

Noted sir! Thank you!

Sergey Alexandrovich Kryukov 16-Feb-16 20:39pm

You are welcome.
—SA

BillWoodruff 16-Feb-16 1:46am

A "List of Lists" will do.

Maciej Los 16-Feb-16 2:12am

Or... List(Of Tuple(Item1, Item2))
:)

bjay tiamsic 16-Feb-16 19:00pm

Thank you so much, how about List with 2 parameters? I just searched it, I can use this to broaden may vocabulary in programming. THank you for responding and giving idea. I really appreciate it

BillWoodruff 16-Feb-16 11:40am

It may be helpful to keep in mind that programmers use the word "Array" to refer to something very specific: a data structure that may have one, or more, "dimensions," and which accessed by the use numeric indexes.

However, "array" is also, in English, a general term that can be loosely used to describe any collection, and it has other meanings, as well, as in the military use "Napoleon's artillery, arrayed on the field of battle like a ...", or the sense of some form of display, often remarkable, elegant, showing-off wealth, etc.,: "she arrived at the Academy Awards arrayed in diamonds worth 100,000 U.S. Dollars, from Val Cleef and Arpels."

So, when talking "tech" probably better to use word 'Array' carefully :)

3 solutions

Solution 1

To access the list item you can use the index as you're doing above.

But to take the object value you have to cast the list object to OrderField and then access the property normally.

C#

((OrderField)listOrderBy[i]).OrderField

Since the list is strongly typed, you might not even need to cast it explicitly.

This is the equivalent of creating new element

C#

OrderField of = new OrderField(1, 'test');
Console.Write(of.OrderField);

would print the word test.

Posted 15-Feb-16 20:54pm

Sinisa Hajnal

Updated 15-Feb-16 20:55pm

v2

Solution 2

I'm not sure what you want to achieve, but it seems you want to sort an array based on another one.

As i mentioned in comment to the Bill's comment, you can use List<Tuple<int, string>>
For example:

C#

List<Tuple<int, string>> a = new List<Tuple<int, string>>(){
	Tuple.Create(1, "1"),
	Tuple.Create(2, "2"),
	Tuple.Create(3, "3"),
	Tuple.Create(4, "4"),
	Tuple.Create(14, "14"),
	Tuple.Create(45, "45"),
	Tuple.Create(6, "6"),
	Tuple.Create(16, "16"),
	Tuple.Create(66, "66"),
	Tuple.Create(100, "100"),
	};

var b = a.OrderBy(x=>x.Item1);
//returns ordered list based on first item (integer): 1, 2, 3 ... 100
var c = a.OrderBy(x=>x.Item2);
//returns ordered list based on secod item (string): 1, 100, 14, 16 ... 66

In case i was wrong, please clarify your question using "Improve question" widget (green link at the right-bottom corner of the question).

Posted 15-Feb-16 22:13pm

Maciej Los

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bjay tiamsic · Accepted Answer · 2016-02-16T13:05:00

Hi All!! I appreciate you response and I am really grateful for helping people like me.

I was able to make a research and this is what I found which worked for me
I created a class

C#

public class OrderFields
    {
        public int OrderNo { get; set; }
        public string OrderField { get; set; }

        public OrderFields(int num, string field)
        {
            OrderNo = num;
            OrderField = field;
        }
    }

protected void lnkStep3(object sender, EventArgs e)
{
        var newOrderByFields = new List<OrderFields>();
        newOrderByFields = listOrderBy;
        for (int i = 0; i <= listOrderBy.Count - 1; i++)
        {
            strOrderByFields +=                 newOrderByFields[i].OrderField.ToString()+",";
        }

}

But I will take your suggestions in mind and will try it in my program. Thank you very much! Please continue helping those in need of knowledge. Mabuhay!