• Pascal

var
  _x: Array of integer;
  _s, i: Integer;
begin
  _s := 0;
  //assume _x contains some values
  for i := Low(_x) to High(_x) do _s := _s + _x[i];
end;

• Ada

for E of x loop
   S := S + E;
end loop;

• C

int i,s;
for(i=s=0;i<n;i++)
{
	s+=x[i];
}

• C

int sum = 0;
for (int i = 0; i < n; ++i) {
  sum += x[i];
}

• Caml

List.fold_left (+) 0 l

• Clojure

(defn sum [x] (reduce + x))

(sum [1 20 300])
;;=> 321

• C++

auto s = std::ranges::fold_left(x, 0, std::plus<int>{});

• C++

int s = std::accumulate(x.begin(), x.end(), 0, std::plus<int>());

• C#

var s = x.Sum();

• D

auto s = x.sum();

• Dart

var s = x.fold(0, (a, b) => a + b);

• Elixir

s = Enum.sum(x)

• Erlang

S = lists:sum(X).

• Fortran

   s = sum(x)

• Go

s := 0
for _, v := range x {
	s += v
}

• Haskell

s = sum x

• JS

var s = x.reduce((a, b) => a + b, 0);

• JS

var s = x.reduce((a, b) => a + b)

• Java

int s = 0;
for (int i : x) {
  s += i;
}

• Java

BigInteger s = new BigInteger(valueOf(x[0]));
for (int i = 1, n = x.length; i < n; ++i)
    s = s.add(new BigInteger(valueOf(x[i])));

• Java

BigInteger s = stream(x)
    .mapToObj(String::valueOf)
    .map(BigInteger::new)
    .reduce(BigInteger::add)
    .get();

• Java

int i = 1, n = x.length, s = x[0];
while (i < n) s = s + x[i++];

• Java

int s = of(x).sum();

• Kotlin

val numbers = listOf(1, 2, 3, 4)
val sum = numbers.sum()

• Lisp

(reduce #'+ x)

• Lua

s = 0
for i,v in ipairs(x) do
   s = s + v
end

• Obj-C

id s=[x valueForKeyPath:@"@sum.self"];

• PHP

$s = array_sum($x);

• Perl

$s = sum(@x);

• Python

s = reduce(add, x)

• Python

s = sum(x)

• Ruby

s = x.reduce(:+)

• Ruby

s = x.sum

• Rust

let s = x.iter().sum::<i32>();

• Rust

x.iter().sum()

• Scala

val s = x.sum()

• Scheme

(define s (fold-right + 0 x))

• Scheme

(define s (apply + x))

• Scheme

(define s (foldr + 0 x))

• Scheme

(define s (apply fx+ x))

• Scheme

(define s (apply + x))

• Smalltalk

s := x sum.

• VB

Dim s As Integer = x.Sum()