1# Optional
2
3- `v::optional(v $rule)`
4
5Validates if the given input is optional or not. By _optional_ we consider `null`
6or an empty string (`''`).
7
8```php
9v::optional(v::alpha())->validate(''); // true
10v::optional(v::digit())->validate(null); // true
11```
12
13
14***
15See also:
16
17  * [NoWhitespace](NoWhitespace.md)
18  * [NotBlank](NotBlank.md)
19  * [NotEmpty](NotEmpty.md)
20  * [NotOptional](NotOptional.md)
21  * [NullType](NullType.md)
22