> For the complete documentation index, see [llms.txt](https://docs.onum.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.onum.com/pipelines/actions/transformation/field-transformation/field-transformation-operations/utils/substring.md).

# Substring

## Description

This operation extracts a portion of a string based on specified start and end positions or lengths. It is a versatile tool for extracting parts of text or binary data.

***

## Data types

These are the input/output expected data types for this operation:

### Input data

`String` - Input string or data from which you want to extract a portion.

### Output data

`String` - Specified substring.

***

## Parameters

These are the parameters you need to configure to use this operation (mandatory parameters are marked with a <mark style="color:red;">**\***</mark>):

<details>

<summary>Start Index<mark style="color:red;"><strong>*</strong></mark></summary>

The starting index from where the substring will be extracted (starting from position 0).

</details>

<details>

<summary>Length</summary>

The length of the substring to extract. If not specified, the extraction will continue to the end of the string.

</details>

***

## Example

Suppose you want to extract a specified substring from your input data:

1. In your Pipeline, open the required [Action](/pipelines/actions.md) configuration and select the input **Field**.
2. In the **Operation** field, choose **Substring**.
3. Set **Start Index** to `3`.
4. Set **Length** to `9`.
5. Give your **Output field** a name and click **Save**.

For example, with the parameters specified above, you'll get the following substring from this text:

```
+34678987678 -> 678987678
```

{% hint style="info" %}
You can try out operations with specific values using the **Input** field above the operation. You can enter the value in the example above and check the result in the **Output** field.
{% endhint %}