Sum and other algorithm functions

[Andrea Fontana via Digitalmars-d-learn]

On Thursday, 10 September 2015 at 13:48:16 UTC, Namal wrote:
> Hello,
>
> how can I define the range for the sum function which I want to 
> sum up? For instance how do I sum up the first 3 elements of an 
> array
>
> int[] a = [1,2,3,4,5,6,7,8,9];
>
> or the last 3?

In this case, you can simply slice array using   a[0..3] or 
a[$-3..$].

If you have a range you can use take() and/or drop()

void main()
{
	
	int[] a = [1,2,3,4,5,6];
	
	writeln(a[0..3]);
	writeln(a[$-3..$]);
	writeln(a.take(3));
	writeln(a.drop(a.length-3));
	
}