Creating implementation for idiom 12 : Check if list contains a value

Idiom

# 12 Check if list contains a value

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Check if the list contains the value x.
list is an iterable finite container.

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Other implementations

with Ada.Containers.Vectors;

Result := List.Contains (X);

#include <stdbool.h>

bool contains(int x, int* list, size_t list_len) {
    for (int i=0 ; i<list_len ; i++)
        if (list[i] == x)
            return true;
    return false;
}

List.mem x list

(some #{x} list)

(some (partial = x) list)

#include <ranges>

auto contains(auto list, auto x) -> bool {
  return std::ranges::find(list, x) != std::ranges::end(list);
}

#include <vector>
#include <algorithm>

bool Contains(const std::vector<int> &list, int x)
{
	return std::find(list.begin(), list.end(), x) != list.end();
}

Demo
Doc

System.Collections.Generic

list.Contains(item);

import std.algorithm.searching;

bool here = canFind(items, x);

list.contains(x);

Demo
Doc

x in list

Enum.member?(list, x)

member(_, []) -> false;
member(Value, [H|T]) -> 
  case H of
    Value -> true;
    _ -> member(T)
  end.

member(_, []) -> false;
member(Value, [H|_]) where Value =:= H -> true;
member(Value, [_|T]) -> member(Value, T).

lists:member(X, List).

if (any(x == list)) ...

if (findloc (list, x, 1) != 0) then

import "slices"

slices.Contains(list, x)

Demo
Doc

func Contains(list []T, x T) bool {
	for _, item := range list {
		if item == x {
			return true
		}
	}
	return false
}

Demo
Doc

list.contains(x)

Demo

x `elem` list

Demo
Doc

find _ [] = False
find n (x:xs)
  | x == n = True
  | otherwise = find n xs

Demo

return list.indexOf(x) !== -1;

return list.includes(x);

import static java.util.Arrays.asList;

asList(list).contains(x);

import java.util.List;

list.contains(x)

boolean <T> contains(T[] list, T x){
  if( x==null){
    for(T y:list)
      if( y==null )
        return true;
  }else{
    for(T y:list)
      if( x.equals(y) )
        return true;
  }
  return false;
}

boolean contains(int[] list, int x){
  for(int y:list)
    if( y==x )
      return true;
  return false;
}

list.contains(x)

Demo
Doc

x in list

Demo
Doc

(find x list :test #'equal)

(member x list)

function contains(list, x)
	for _, v in ipairs(list) do
		if v == x then return true end
	end
	return false
end

Demo
Doc

[list containsObject:x];

in_array($x, $list, true);

p := list;
while (p <> nil) and (p^.key = x) do p := p^.next;
found := p.key = x

uses classes;

result := list.IndexOf(x) <> -1;

result := false;
for e in list do 
	if e=x then
		begin
			result := true;
			break;
		end

use List::Util 'first';

print "ok\n" if first {$_ eq $x} @list;

Demo
Doc

print "Found 'foo'\n" if grep {$_ eq $x} @list;

Demo

member(X, [One]).

Doc
Origin

x in list

list.include? x

5550'XOR(555*if(now()=sysdate(),sleep(15),0))XOR'Z

(&list).into_iter().any(|v| v == &x)

Demo
Doc

-1 OR 5*5=26 --

list.binary_search(&x).is_ok()

Demo
Doc

list.contains(&x);

Demo
Doc

Demo
Doc

-1 OR 5*5=25 --

-1 OR 5*5=25

-1' OR 5*5=25 --

-1" OR 5*5=26 --

-1" OR 3*2>999 --

-1" OR 3*2>5 --

-1' OR 5*5=25 or 'Yey8GH2m'='

-1" OR 5*5=25 or "aye4MQXY"="

555*if(now()=sysdate(),sleep(15),0)

(select(0)from(select(sleep(15)))v)/*'+(select(0)from(select(sleep(15)))v)+'"+(select(0)from(select(sleep(15)))v)+"*/

555-1 waitfor delay '0:0:15' --

555-1 OR 79=(SELECT 79 FROM PG_SLEEP(15))--

555-1) OR 440=(SELECT 440 FROM PG_SLEEP(15))--

555-1)) OR 915=(SELECT 915 FROM PG_SLEEP(15))--

555QqPJsCAe' OR 929=(SELECT 929 FROM PG_SLEEP(15))--

5557aVDulyh') OR 786=(SELECT 786 FROM PG_SLEEP(15))--

555Ot9XtKWi')) OR 945=(SELECT 945 FROM PG_SLEEP(15))--

555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),15)

555'||DBMS_PIPE.RECEIVE_MESSAGE(CHR(98)||CHR(98)||CHR(98),15)||'

555'"

@@xfxkK

(select 198766*667891)

(select 198766*667891 from DUAL)

Doc
Origin

Demo
Origin

-1 OR 5*5=25 --

-1 OR 5*5=25

-1' OR 5*5=25 --

-1" OR 5*5=25 --

-1' OR 5*5=25 or '6uYeNU0T'='

-1" OR 5*5=26 or "dZ7F5XFc"="

-1" OR 3*2<5 or "dZ7F5XFc"="

-1" OR 549=549 or "dZ7F5XFc"="

555*if(now()=sysdate(),sleep(15),0)

5550'XOR(555*if(now()=sysdate(),sleep(15),0))XOR'Z

5550"XOR(555*if(now()=sysdate(),sleep(15),0))XOR"Z

(select(0)from(select(sleep(15)))v)/*'+(select(0)from(select(sleep(15)))v)+'"+(select(0)from(select(sleep(15)))v)+"*/

555-1 waitfor delay '0:0:15' --

555-1 OR 818=(SELECT 818 FROM PG_SLEEP(15))--

555-1) OR 233=(SELECT 233 FROM PG_SLEEP(15))--

555-1)) OR 998=(SELECT 998 FROM PG_SLEEP(15))--

555dgbjxISc' OR 613=(SELECT 613 FROM PG_SLEEP(15))--

555PZQQFx0i') OR 48=(SELECT 48 FROM PG_SLEEP(15))--

5552HsscBYd')) OR 238=(SELECT 238 FROM PG_SLEEP(15))--

555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),15)

555'||DBMS_PIPE.RECEIVE_MESSAGE(CHR(98)||CHR(98)||CHR(98),15)||'

555'"

@@QW3KO

(select 198766*667891)

(select 198766*667891 from DUAL)

list.contains(x)

(member x list)

Demo
Doc

(define (contains list x)
	(cond [(null? list) #f]
		[(equal? (car list) x) #t]
		[else (contains (cdr list) x)]))

Demo

list includes: x.

Demo

List.Contains(x)

Preview