# Regex syntax

## Function

Explains the basic BT regular-expression syntax: create a Regex object with `regex(pattern, flags)`, then call `test`, `match`, or `replace`, or pass it to `String.search`, `String.match`, or `String.replace`.

## Syntax

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

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| pattern | String | No | '' | Regular body. |
| flags | String | No | '' | Flags string. |

## Return value

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

## Example

```bt
rule = regex('^BT$', '')
result = rule.test('BT')

// Output: true
print result
```

## Notes

-Uses Rust regex engine under the hood.
- A Chinese error will be thrown when regular compilation fails.