# `CardBin`

The first 6 or 8 digits of a card number, which name its issuer.

Use it to look up a card's issuer or country, as fraud checks do. For the whole number, use [`PaymentCardNumber`](/docs/types/type-payment-card-number.md).

## Shape

One value, held as text in one set form, with no parts: `42424242`.

## Example

```jadpo
CardBin("424242")
```

`CardBin(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: CardBin)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `4242`, `4242424` or `424242424`.

## Good to know

- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.

## In JSON

A string, in a request, a response or `json.write`:

```json
"424242"
"42424242"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`CardBin` is in the group Money and banking, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `424242` and `42424242`.

### How it is stored

It is stored in one column named for the field, of type `text`. `42424242` is stored as `'42424242'`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `424242` | `424242` |
| `42424242` | `42424242` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>