Office interop excel open workbook

Microsoft Excel is powerful spreadsheet tool with lots of features for data visualization, analysis and documentation. Excel formats data in the form of rows and columns and cells. As a developer, many times you are required to read or write data into an Excel file. There are multiple ways to read and write data in excel programmatically i.e. by using COM Components and using third party components/SDKs.

This tutorial shows you how to Read and Write Excel files in Microsoft C#. We are going to use Microsoft COM Objects i.e. Excel 16 object in our application. Use the following sample C# source code for Excel reading and writing. There are multiple examples discussed in this tutorial to read Excel files using C# and write data back to Excel file.

Table of Contents

• Write data to Excel file
• Read data from Excel file
• Steps to read and write data from Excel using C#
  • Step 1: Create a new C# project in Visual Studio
  • Step 2: Add COM Component Reference i.e. Excel 14 Object
  • Step 3: Import the namespaces in C# code
  • Step 4: Write Data to Excel File
  • Step 5: Read Data from Excel File
  • Step 6: Run the C# Program

Write data to Excel file

The following C# code uses the Excel interop library to create a new Excel instance, open a specified workbook and write text to the first cell of the worksheet. It also includes cleanup code to release resources and ensure that the Excel process is fully closed.

Read data from Excel file

The following C# code also uses the same mechanism to read the data from an Excel sheet. First, it creates a new Excel instance, open a specified workbook and read value from the second cell of the worksheet. It also includes cleanup code to release resources and ensure that the Excel process is fully closed.

Steps to read and write data from Excel using C#

In this tutorial, we are going to use Microsoft Visual Studio 2017 Community Edition.

Step 1: Create a new C# project in Visual Studio

Open up Visual Studio and create a new Windows Desktop application using Visual C#. You can choose any .NET Framework available in your computer. We are going to use .NET Framework 4.6.1.

Step 2: Add COM Component Reference i.e. Excel 14 Object

Next step is to right click on ExcelReaderWriter C# Project under Solution Explorer and choose Add->Reference.

Then choose COM->Type Libraries and select the desired COM Component for Excel. In our case we used Microsoft Excel 16.0 Object Library.

Step 3: Import the namespaces in C# code

Add the following namespaces to import into the code.

Also create a class variable to hold Excel File name i.e.

Step 4: Write Data to Excel File

Add a Button and TextBox controls on the form. Then double click on the button to show up the code view and Visual Studio Automatically creates the button click event handler. Add the code to the handler so that it looks like below:

Step 5: Read Data from Excel File

Create another Button and TextBox control to use for reading the data from Excel file. Add the following code to button click even handler.

Step 6: Run the C# Program

Compile and run the program now. The output should be similar to the one showing below. Enter some data in first text box and click Write button. It will write data to already created Excel file C:data.xlsx. Similarly, you can click on Read button, which will read the data from same Excel file and show it in the second text file.

There are other third party libraries available, which you can use in your code to read and write Excel files. These libraries are available both under open source as well as commercially available. Few of them are:

• https://github.com/nissl-lab/npoi – Open Source, Apache 2.0 License
• https://github.com/EPPlusSoftware/EPPlus – Commercially Available
• https://github.com/JanKallman/EPPlus – Available under LGPL
• https://bytescout.com/products/developer/spreadsheetsdk/bytescoutspreadsheetsdk.html – Commercially Available

• Download source files — .NET 4.0 Office 2007 — 975.7 KB
• Download source files — .NET 1.0 Office XP — 347.5 KB

Introduction 

Note: This article has been updated to interact with Office 2007. I left the old .NET 1.0 solution for Office XP available for download for reference (in case you are using an old version of Office).

This is a short introduction to opening an existing Microsoft Excel spreadsheet using Visual C# .NET. The computer must have Excel installed on the system for this code to run properly. The Excel assembly is used to open and manipulate Excel spreadsheets.

Code Explanation

First, the Excel assembly must be added to the project. To do this you must add a reference to the Microsoft.Office.Interop.Excel library by going to the Project -> Add Reference  menu item. Go to the .NET tab of the dialog box that pops up and scroll down the Microsoft.Office.Interop.Excel list item. Double click on it and press OK. This adds the reference to your project. In the «using» section of your code, type

using Excel = Microsoft.Office.Interop.Excel; 

Once the assembly is added to the project, a new application needs to be created:

Excel.Application excelApp = new Excel.Application();

If you want to make Excel visible to the user you have to set the Visible property to true, the default is false.  

excelApp.Visible = true;

The code above opens the Excel application, in order to use the application, you have to open a workbook by creating a Workbook object. You can open a new blank workbook by using the following code:

Excel.Workbook newWorkbook = excelApp.Workbooks.Add();

The preceding code opens a blank workbook with one sheet. The .Add method optionally takes a template object.  If the parameter is left blank, the default template will be used (like when you open Excel manually).

If you want to open an existing document for editing instead of creating a new one, you can use the following code to open the Workbook object: 

string workbookPath = "c:/SomeWorkBook.xls";
Excel.Workbook excelWorkbook = excelApp.Workbooks.Open(workbookPath,
        0, false, 5, "", "", false, Excel.XlPlatform.xlWindows, "",
        true, false, 0, true, false, false);

The preceding code may need a little explanation. The workbookPath is of course the path to the existing spreadsheet that you want to open, and if using .NET 4.0 and the Office 2007 library (Microsoft.Office.Interop.Excel library), it is the only parameter required. The rest of the excelApp.Workbooks.open parameters are a little less obvious. The following is the list of parameters that are passed to the function:

• WorkBooks.open(string Filename, object UpdateLinks, object ReadOnly, object Format, object Password, object WriteResPassword, object ReadOnlyRecommend, object Origin, object Delimiter, object Editable, object Notify, object Converter, object AddToMru, object Local, object CorruptLoad )

To view the documentation on this function, follow the link to Microsoft’s website for further explanation of the function at:
http://msdn.microsoft.com/en-us/library/bb179167%28v=office.12%29.aspx

Once the workbook is either created or opened, you must create a Sheets object that holds the Worksheets within the workbook. The following code will get all of the sheets in the workbook you previously opened.

Excel.Sheets excelSheets = excelWorkbook.Worksheets;

Now that you have the collection of Worksheets, you must get an individual sheet edit data within.

string currentSheet = "Sheet1";
Excel.Worksheet excelWorksheet = (Excel.Worksheet)excelSheets.get_Item(currentSheet);

In the preceding code, you have to type cast the excelSheets.get_Item(string) method because it returns an
object. Now that you have the sheet you are ready to access individual cells with the following code:

Excel.Range excelCell = 
        (Excel.Range)excelWorksheet.get_Range("A1", "A1");

The get_Range function must take two parameters. If the two parameters are equal, a single cell is selected; otherwise a range of cells will be selected. Again you have to type cast the return value of the method. Once you have a cell object, your can set its value using the .Value2 property, or use any of the other properties to manipulate ranges of cells.