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C # LINQ add element to end of array

I have an int [] array. I need to take an int and add it to the end of an array without affecting the position of other elements in that array. Using C # 4 and LINQ, what is the most elegant way to achieve this?

My code:

 int[] items = activeList.Split(',').Select(n => Convert.ToInt32(n)).ToArray();
 int itemToAdd = ddlDisabledTypes.SelectedValue.ToInt(0);

 // Need final list as a string
 string finalList = X

Thanks for any help!

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6 answers


The easiest way is to slightly change the expression. Convert to first List<int>

, then add element and then convert to array.

List<int> items = activeList.Split(',').Select(n => Convert.ToInt32(n)).ToList();
int itemToAdd = ddlDisabledTypes.SelectedValue.ToInt(0);
items.Add(itemToAdd);

// If you want to see it as an actual array you can still use ToArray
int[] itemsAsArray = items.ToArray();

Based on your last line, although it seems like you want to return all information as value string

. If so, you can do the following



var builder = new StringBuilder();
foreach (var item in items) {
  if (builder.Length != 0) {
    builder.Append(",");
  }
  builder.Append(item);
}
string finalList = builder.ToString();

If the overall goal is to simply add another element to the end of the string, it is much more efficient to do so directly instead of converting to a collection int

and then back to a string.

int itemToAdd = ddlDisabledTypes.SelectedValue.ToInt(0);
string finalList = String.IsNullOrEmpty(activeList)
  ? itemToAdd.ToString()
  : String.Format("{0},{1}", activeList, itemToAdd);
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Try it items.Concat(new[] { itemToAdd });

.



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Your example code seems really convoluted to fit the conditions

using your code

List<int> items = activeList.Split(',').Select(n => Convert.ToInt32(n)).ToList();  
items.Add(ddlDisabledTypes.SelectedValue.ToInt(0));  

string finalList = String.Join(',',items.ToArray());

Just manipulate the string

int itemToAdd = ddlDisabledTypes.SelectedValue.ToInt(0);  
string finalList = String.IsNullOrWhiteSpace(activeList) ? 
                                           itemToAdd.ToString() :
                                           itemToAdd + string.format(",{0}",itemToAdd);
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Why not:

 List<int> items = activeList.Split(',').Select(n => Convert.ToInt32(n)).ToList();
 int itemToAdd = ddlDisabledTypes.SelectedValue.ToInt(0);
 items.Add(itemToAdd);

EDIT:

And further, if you want to have an int array:

int[] array = items.ToArray();
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Why not just add the element as string

directly?

string finalList = items + "," + itemToAdd;

int

automatically converted string

to concatenations.

if items

can be null

or empty then change the expression to

string finalList = String.IsNullOrEmpty(items) ? 
                     itemToAdd.ToString() : items + "," + itemToAdd;
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I don't understand why you are using String converted to array converted to String ..? Could this be what you need?

string finalList = activeList + "," + ddlDisabledTypes.SelectedValue;
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