• Namal (6/6) Sep 10 2015 Hello,
• anonymous (4/13) Sep 10 2015 First you slice the first/last 3, then you sum them.
• Andrea Fontana (15/21) Sep 10 2015 In this case, you can simply slice array using a[0..3] or

"Namal" <sotis22 mail.ru> writes:

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?

anonymous <anonymous example.com> writes:

On Thursday 10 September 2015 15:48, 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?

First you slice the first/last 3, then you sum them.

first 3: a[0 .. 3].sum
last 3: a[$ - 3 .. $].sum

"Andrea Fontana" <nospam example.com> writes:

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));
	
}