Question

I m reading data from a source as array. a[n]

I need to add one more element to the array.

Once i get the array, i create a new array with capacity n+1 and copy all the elements to the new array and put the new element as the last element of the array.

I can do this.

Is there a better way to do this? especially with Linq?

Answer 1

What you have described is really the only way to do it. Arrays cannot be resized in .NET, so we have to allocate a new array and copy the old into it. For example, this is how Array.Resize works. LINQ is not really a help here, and if it was, it would just be projecting the existing array into a new one anyway – which is exactly what we’ve just described.

If you find you need to resize the array often, you should consider using an ArrayList or, if possible, a strongly-typed List<T>.

Edit:
If you are simply getting an Array from some method you cannot control, but within your code you could use an IEnumerable<T> instead, you can use LINQ to lazy-enumerate and spare the extra array allocation:

var mySequence = originalArray.Concat(new[]{myobj});

//snip

foreach(var item in mySequence)
{
    //do stuff
}

It’s only when calling ToArray() that we incur the extra overhead. Otherwise we’re simply doing a single enumeration over the original array and then sneaking the extra item(s) in at the end.