# Idiom #12 Check if list contains a value

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

(some #{x} list)
(some (partial = x) list)
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
#include <vector>
#include <algorithm>
bool Contains(const std::vector<int> &list, int x)
{
return std::find(list.begin(), list.end(), x) != list.end();
}
System.Collections.Generic
list.Contains(item);
import std.algorithm.searching;
bool here = canFind(items, x);
list.contains(x);
Enum.member?(list, x)
x in list
lists:member(X, List).
member(_, []) -> false;
member(Value, [H|_]) where Value =:= H -> true;
member(Value, [_|T]) -> member(Value, T).
member(_, []) -> false;
member(Value, [H|T]) ->
case H of
Value -> true;
_ -> member(T)
end.
if (findloc (list, x, 1) != 0) then
if (any(x == list)) ...
func Contains(list []T, x T) bool {
for _, item := range list {
if item == x {
return true
}
}
return false
}
list.contains(x)
x `elem` list
find _ [] = False
find n (x:xs)
| x == n = True
| otherwise = find x xs
return list.indexOf(x) !== -1;
return list.includes(x);
import java.util.List;
list.contains(x)
boolean contains(int[] list, int x){
for(int y:list)
if( y==x )
return true;
return false;
}
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;
}
list.contains(x)
x in list
(member x list)
function contains(list, x)
for _, v in pairs(list) do
if v == x then return true end
end
return false
end
[list containsObject:x];
in_array(\$x, \$list, true);
result := false;
for e in list do
if e=x then
begin
result := true;
break;
end
uses classes;
result := list.IndexOf(x) <> -1;
List::Util 'first'
print "ok\n" if first {\$_ eq 'needle'} @haystack;
# To check an array for a value:
print "Found 'foo'\n" if grep { \$_ eq 'foo' } @a_list;

# To check a map for a value:
print "Found 'bar'\n" if exists \$map{bar};
member(X, [One]).
x in list
list.include? x
list.contains(&x);
(&list).into_iter().any(|v| v == &x)
list.iter().any(|v| v == &x)
list.contains(x)
(define (contains list x)
(cond [(null? list) #f]
[(equal? (car list) x) #t]
[else (contains (cdr list) x)]))
List.Contains(x)

#### Idiom created by

programming-idioms.org