Question

I have an int[] array. I need to take an int and append it to the end of the array without affecting the position of the other items 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!

Answer 1

The easiest way is to change your expression around a bit. First convert to a List<int>, then add the element and then convert to an 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 though it seems like you want to get all of the information back as a string value. If so then 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 though is to just append one more item to the end of a string then it’s much more efficient to do that directly instead of converting to an int collection 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);