# Isbn

- `v::isbn()`

Validates whether the input is a valid [ISBN][] or not.

```php
v::isbn()->isValid('ISBN-13: 978-0-596-52068-7'); // true
v::isbn()->isValid('978 0 596 52068 7'); // true
v::isbn()->isValid('ISBN-12: 978-0-596-52068-7'); // false
v::isbn()->isValid('978 10 596 52068 7'); // false
```

## Templates

### `Isbn::TEMPLATE_STANDARD`

| Mode       | Template                             |
| ---------- | ------------------------------------ |
| `default`  | {{subject}} must be a valid ISBN     |
| `inverted` | {{subject}} must not be a valid ISBN |

## Template placeholders

| Placeholder | Description                                                      |
| ----------- | ---------------------------------------------------------------- |
| `subject`   | The validated input or the custom validator name (if specified). |

## Categorization

- Identifications

## Changelog

| Version | Description |
| ------: | ----------- |
|   2.0.0 | Created     |

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See also:

- [Imei](Imei.md)
- [Luhn](Luhn.md)

[ISBN]: https://www.isbn-international.org/content/what-isbn "International Standard Book Number"