> 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-v10/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 | pattern \[System.String] – Regular expression pattern to match
searchIn \[System.String] – String to search for a match
replaceWith \[System.String] – Replacement string
|
**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
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.
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