# String.substr

## Function

Truncate the string by length starting from the specified position.

## Syntax

```bt
string.substr(start, length)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| start | Int | No | 0 | Starting character position; a negative number means counting backwards from the end. |
| length | Int | No | String length | Truncation length; negative numbers are treated as 0. |

## Return value

| Type | Description |
| ------ | ------ |
| String | Returns the new string after interception. |

## Example

```bt
text = 'hello BT'
result = text.substr(6, 2)

// Output: BT
print result
```

## Notes

- Unlike the second parameter of slice, the second parameter of substr represents the length.