> ## Documentation Index
> Fetch the complete documentation index at: https://persian-tools.usestrict.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Card Number

> Validate Iranian bank card numbers (Luhn + BIN whitelist) and look up the issuing bank.

Two complementary functions for working with Iranian card numbers: `verifyCardNumber` (validation) and `getBankNameFromCardNumber` (BIN-based bank lookup). For extracting card numbers from free text, see the [Extract Card Numbers](../banking/extract-card-numbers) page.

## Functions

### `verifyCardNumber(digits)`

```ts theme={null}
import { verifyCardNumber } from "@persian-tools/persian-tools";

verifyCardNumber("6037701689095443"); // true
verifyCardNumber("6037 7016 8909 5443"); // true (whitespace stripped)
verifyCardNumber("4111111111111111"); // false (Luhn-valid but non-Iranian BIN)
verifyCardNumber("0000000000000000"); // false (all-zero middle blocks)
verifyCardNumber(undefined); // undefined
```

Return type: `boolean | undefined` (returns `undefined` for falsy input).

#### Two-stage algorithm

1. Whitespace strip + format check: `/^\d{16}$/`.
2. Reject if middle 10 digits (`slice(1,11)`) OR last 6 digits (`slice(10,16)`) are all zero.
3. The 6-digit BIN must be in `iranianBankPrefixes` — non-Iranian cards are rejected even if Luhn-valid.
4. Standard Luhn checksum.

### `getBankNameFromCardNumber(digits)`

```ts theme={null}
import { getBankNameFromCardNumber } from "@persian-tools/persian-tools";

getBankNameFromCardNumber("6219861034529007"); // "بانک سامان"
getBankNameFromCardNumber("603799"); // "بانک ملی ایران"
getBankNameFromCardNumber("9999999999999999"); // null — BIN not in table
getBankNameFromCardNumber("123"); // null — too short
getBankNameFromCardNumber(undefined); // undefined
```

Return type: `string | null | undefined` — see [Bank Name from Card Number](../banking/bank-name) for the dedicated page.

## Composition

```ts theme={null}
import { autoConvertDigitsToEN, verifyCardNumber, getBankNameFromCardNumber } from "@persian-tools/persian-tools";

function inspect(raw: string) {
	const norm = autoConvertDigitsToEN(raw.trim());
	const valid = verifyCardNumber(norm) === true;
	return {
		valid,
		bank: valid ? getBankNameFromCardNumber(norm) : null,
	};
}
```

## Pitfalls

* **Both return `undefined` on falsy input** — use `=== true` / `=== "string"`, not truthy checks.
* **Non-Iranian Luhn-valid cards (e.g. test `4111...`) are rejected.** Intentional.
* **Persian/Arabic digit input is not normalized** — pre-convert with `autoConvertDigitsToEN`.
* **To extract card numbers from text**, use `extractCardNumber` (singular) from [Extract Card Numbers](../banking/extract-card-numbers). There is no `extractCardNumbers` (plural) export.
* **Adding new BINs**: edit both the `iranianBankPrefixes` set (verifier) and the `cardBank` table (lookup) in lock-step.

## Source

`src/modules/verifyCardNumber/index.ts`, `src/modules/getBankNameFromCardNumber/index.ts` · Tests: `test/verifyCardNumber.spec.ts`, `test/getBankNameFromCardNumber.spec.ts`