> For the complete documentation index, see [llms.txt](https://documentation.astera.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.astera.com/astera-data-stack-v8/functions/regular-expressions/replaceregex.md).

# ReplaceRegEx

| **Name**    | ***ReplaceRegEx***                                                                                                                                                                           |
| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Syntax      | ReplaceRegEx (String pattern, String searchIn, String replaceWith)                                                                                                                           |
| Purpose     | To scan the input string for the specified pattern and replace it with the value specified in replaceWith parameter.                                                                         |
| Description | If the pattern is found, it is replaced with the ‘replaceWith’ parameter, and the resulting value is returned. Otherwise, the original value is returned.                                    |
| Return Type | String                                                                                                                                                                                       |
| Parameters  | <p>pattern \[System.String] – Regular expression pattern to match</p><p>searchIn \[System.String] – String to search for a match</p><p>replaceWith \[System.String] – Replacement string</p> |

![](https://github.com/astera-software/Astera_Data_Stack_v9/blob/main/.gitbook/assets/0%20\(6\).png)

**Example**

In this example, we will pass the required parameters to the function transformation object using a *Variables* object.

Where,

*pattern* = (Mr|Mrs).

*searchIn* = Mr. John

*replaceWith* = Sir

![](https://github.com/astera-software/Astera_Data_Stack_v9/blob/main/.gitbook/assets/1%20\(6\).png)

In the output window, you can see that Astera has returned a string value with the appended *replaceWith* value, as the specified *pattern* value was matched with the *searchIn* value.

![](https://github.com/astera-software/Astera_Data_Stack_v9/blob/main/.gitbook/assets/2%20\(6\).png)


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