Check if array contains element in D

Question

for associative arrays we can write

if( elem in array) { .. }

what do we write for a simple array? I want to write validation e.g.

enforce(input in [10,20,40]);

Answer 1

in sadly doesn't work on array. You must use canFind or search defined in std.algorithm http://dlang.org/phobos/std_algorithm.html. Since you only want to know if it's present, not where it is, canFind is the right tool.

import std.algorithm: canFind;

if (my_array.canFind(42)) { stuff }

Answer 2

In addition to canFind, there is also countUntil which will get you the index of the first occurrence.

Note that D's "in" keyword searches the associative array's keys and not its values :

string[string] array = [
    "foo" : "bar"
];

writeln(("foo" in array) != null); // true
writeln(("bar" in array) != null); // false