title	Walkthrough Developing a Managed-Code UDF
description	This walkthrough describes the process for developing Excel Services user-defined functions (UDFs) using Microsoft Visual C#.
ms.date	06/07/2022
ms.assetid	e6a00833-0606-4a7d-91c3-b89a6e340348
ms.localizationpriority	medium

Walkthrough: Developing a Managed-Code UDF

This walkthrough describes the process for developing Excel Services user-defined functions (UDFs) using Microsoft Visual C#.

During this walkthrough, you will learn how to:

Create a project using the Microsoft Visual Studio 2005 class library project template.
Add a reference to Microsoft.Office.Excel.Server.Udf.dll.
Write UDFs for use in Excel Services.
Create a workbook to call custom functions from cells.
Test and run UDFs in Excel Services.

Prerequisites

In order to complete this walkthrough, you will need:

Microsoft SharePoint Server 2010

[!NOTE] The easiest way to get all you need on the server is to do a basic, stand-alone install. All you need to add on top of that is a trusted location.
Excel
Visual Studio or a similar Microsoft .NET Framework-compatible development tool
To enable running the UDF assembly
A trusted SharePoint document library in which to store a workbook, and to allow the workbook to call UDFs by setting the AllowUdfs value to true
A sample workbook that calls the UDF stored in a trusted SharePoint document library
Permissions to view and publish a workbook to a SharePoint document library

[!NOTE] For more information about setting permissions, see the Windows SharePoint Services 3.0 documentation.
To create the workbook using Excel
To save the workbook as an .xlsx or .xlsb file

[!NOTE] For more information about how to trust a location, how to enable UDFs, and how to set the AllowUdfs flag, see Step 3: Deploying and Enabling UDFs.