C# Array Move Item (Not ArrayList/Generic List)

Question

Have an object which is an array (not arraylist or generic) that could hold a set of anything...

[[One],[Two],[Three],[Four]]

Want to move [Four] to in front of [Two] e.g. oldIndex = 3, newIndex = 1 so the result would be...

[[One],[Four][Two],[Three]]

Whats the most effient way to do this in .NET 2.0, e.g.

PropertyInfo oPI = ObjectType.GetProperty("MyArray", BindingFlags.Public | BindingFlags.Instance);
object ObjectToReorder = oPI.GetValue(ParentObject, null);
Array arr = ObjectToReorder as Array;
int oldIndex = 3;
int newIndex = 1;
//Need the re-ordered list still attached to the ParentObject

thanks in advance

Wyzfen · Accepted Answer · 2009-03-20 21:47:46Z

6

void MoveWithinArray(Array array, int source, int dest)
{
  Object temp = array.GetValue(source);
  Array.Copy(array, dest, array, dest + 1, source - dest);
  array.SetValue(temp, dest);
}

answered Mar 20, 2009 at 21:47

Wyzfen

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3 Comments

Mark Over a year ago

thats more like it, just goes to show that its not about how many questions you've answered its about how good the answers are. I had no idea you could copy an array onto itself. I guess thats how the ArrayList does Insert?,i tried the code using reflector but I could find the ArrayList class thanks

Mark Over a year ago

That question looks like it was too easy for you, if you can could you try to answer this other question i've posted... stackoverflow.com/questions/668356/…

Whyser Over a year ago

I really don't understand how this answer can get any up-votes at all. The solution given here only works in OP's very specific example. The method should be named MoveWithinArrayInOneSpecificCase(...). For example, if we try to move an element from front to back we get negative length-parameter (just one of the possible errors in this method).

JaredPar · Accepted Answer · 2009-03-19 00:13:51Z

3

Try this

Array someArray = GetTheArray();
object temp = someArray.GetValue(3);
someArray.SetValue(someArray.GetValue(1), 3);
someArray.SetValue(temp, 1);

answered Mar 19, 2009 at 0:13

JaredPar

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1 Comment

Mark Over a year ago

If I step through your code with the array i gave then i get a different array to the one I required... ### 1. Array someArray = GetTheArray(); [[One],[Two],[Three],[Four]] ### 2. object temp = someArray.GetValue(3); [[One],[Two],[Three],[Four]] temp is [Four] ### 3. someArray.SetValue(someArray.GetValue(1), 3); someArray.GetValue(1) is [Two] [[One],[Two],[Three],[Two]] ### 4. someArray.SetValue(temp, 1); [[One],[Four],[Three],[Two]] ### I wanted [[One],[Four],[Two],[Three]] (i.e. Move [Four] in-front of [Two])

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