# Regex grouping and flags

## Function

Describes grouping, capturing, and capturing group return rules for String.match.

## Syntax

```bt
regex(pattern, flags)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| pattern | String | No | '' | Can contain (...) capture groups. |
| flags | String | No | '' | Regular flags. |

## Return value

| Type | Description |
| ------ | ------ |
| Regex | Returns a Regex object. |

## Example

```bt
result = 'BT-2026'.match(regex('^([A-Z]+)-([0-9]+)$', ''))

// Output: ["BT-2026","BT","2026"]
print result
```

## Notes

- When String.match receives a Regex without g, item 0 is a complete match and subsequent items are capturing groups.