Idiom #166 Concatenate two lists

Create the list ab containing all the elements of the list a, followed by all the elements of the list b.

val ab = a ++ b

val ab = a ::: b

(def ab (concat a b))

auto ab = a;
ab.insert (ab.end (), b.begin (), b.end ());

System.Linq

var list1 = new List<int>(){1,2,3};
var list2 = new List<int>(){4,5,6};

var list3 = list1.Concat(list2);

int[] a, b;
auto ab = a ~ b;

std.range;

int[] a, b;
auto ab = chain(a, b);

var ab = a + b;

ab = a ++ b

AB = A ++ B.

real, dimension(:), allocatable :: ab

ab = [a, b]

ab := make([]T, len(a)+len(b))
copy(ab, a)
copy(ab[len(a):], b)

var ab []T
ab = append(append(ab, a...), b...)

ab := append(a, b...)

ab = a ++ b

var ab = a.concat(b);

var ab = new ArrayList<>(a);
ab.addAll(b);

import java.util.ArrayList;
import java.util.List;

List<?> ab = new ArrayList<>(a) {{ addAll(b); }};

val ab = a + b

(setf ab (append a b))

ab = {}

table.foreach(a, function(k, v) table.insert(ab, v) end)
table.foreach(b, function(k, v) table.insert(ab, v) end)

ab = {}

table.move(a, 1, #a, 1, ab)
table.move(b, 1, #b, #ab + 1, ab)

@import Foundation;

NSArray *ab=[a arrayByAddingObjectsFromArray:b];

$ab = array_merge($a, $b);

uses classes;

var
  a,b,ab: TList;

...
  ab := TList.Create;
  ab.Assign(a);
  ab.AddList(b);
...

@ab = (@a, @b)

ab = a + b

from itertools import chain

ab = list(chain(a, b))

ab = a + b

let ab = [a, b].concat();

(define ab (append a b))

ab := a,b

Do you know the best way to do this in your language ? New implementation...

< > ⌨

Idiom created by programming-idioms.org

History

Related idioms

Issues