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# Isbn

- `Isbn()`

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

```php
v::isbn()->assert('ISBN-13: 978-0-596-52068-7');
// Validation passes successfully

v::isbn()->assert('978 0 596 52068 7');
// Validation passes successfully

v::isbn()->assert('ISBN-12: 978-0-596-52068-7');
// → "ISBN-12: 978-0-596-52068-7" must be an ISBN

v::isbn()->assert('978 10 596 52068 7');
// → "978 10 596 52068 7" must be an ISBN
```

## Templates

### `Isbn::TEMPLATE_STANDARD`

|       Mode | Template                        |
| ---------: | :------------------------------ |
|  `default` | {{subject}} must be an ISBN     |
| `inverted` | {{subject}} must not be an ISBN |

## Template placeholders

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

## Categorization

- Identifications

## Changelog

| Version | Description       |
| ------: | :---------------- |
|   3.0.0 | Templates changed |
|   2.0.0 | Created           |

## See Also

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

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