C# Open Excel File Programmatically (Code Example Tutorial)

We are all aware that the Excel spreadsheet has been around for a long time. It is primarily used for calculations and graphing data, making it perfect for creating financial models, analyzing the cost-effectiveness of various advertising campaigns, and many other types of analysis.

While it should be a straightforward process, creating an Excel file programmatically can be difficult because of the number of rows and columns involved. Many tasks are quickly done with Excel, such as selecting or sorting data. However, there is no easy way to do it when you need to create a new spreadsheet from scratch. Creating XLSX files programmatically requires many lines of code, something which can get complicated very quickly.

Excel files are harder to create programmatically because they need to be set up with data and formulas before they can be used. The different kinds of data you store in the spreadsheet can significantly impact how difficult it is to create an Excel file. If you need to create an Excel file with a lot of data, you will probably find it more complicated than if there are fewer columns and rows. Secondly, the formatting of your spreadsheet could also make creating an Excel file difficult. For example, suppose you want the columns in your spreadsheet to be aligned at all times. In that case, this will make generating a new spreadsheet more complicated than usual, because you will need to calculate where each column should be, based on other columns in the sheet, and how many rows there should be.

So, we have come up with a solution. We will show how easy it is to create and read Excel files with the IronXL C# library.

IronXL: C# Excel Library

IronXL is a C# Excel library that helps you make more robust spreadsheets. With IronXL, there are no limitations on the number of rows and columns in a spreadsheet. You can have as many rows and columns as you need without adding complex formulas for calculating column widths.

IronXL makes it possible to create workbooks with millions of rows and thousands of columns, which would not be possible without complex calculations or using any other spreadsheet software. With IronXL, there is no limit to the number of rows or columns in your spreadsheet, allowing you to design very high-dimensional models on a single sheet. IronXL is a complete library that will complete all Excel processes. Its fully kitted features will create and read Excel files in C#.

IronXL simplifies the number crunching and data analysis process by providing its users with powerful functions that they can use to work on the data without too much effort. We also do not need to install Microsoft Office on our machine.

The following section will describe how the library can be used to read and write Excel files in C#.

Create a C# .NET Project

Create a new C# Console project in Microsoft Visual Studio. I am using Visual Studio's 2022 version. You can use any version, but the latest version is recommended. When creating a project, choose .NET Framework > 3.0 because it is recommended. You can give any name to your project. You can create a GUI project, too, according to your needs. IronXL supports every template format of the .NET Framework. After completing the project, the next step will be to install the IronXL library.

Install the IronXL Library

Now it's time to install the IronXL library. You must follow the steps below to install it. We will install the library using the NuGet Package Manager.

Go to the Tools option from the main menu bar. Hover on the NuGet Package Manager and select the Manage NuGet Packages for Solution... option from the dropdown menu.

Navigate to NuGet Package Manager in Visual Studio

This will open the NuGet Package Manager tab. Go to the browse tab and search for IronXL. Select IronXL from the search results.

Search for IronXL in NuGet Package Manager

Install the selected library. You will see the IronXL library dependencies in the solution explorer.

IronXL package is added to the project

Now we can use the library in our project. Let's move to the program.cs file and write the code for creating an Excel file.

Code for creating Excel Files

Here is the code for creating an Excel file programmatically using the IronXL C# library.

using IronXL;

// Create a new Excel workbook in XLSX format
WorkBook workbook = WorkBook.Create(ExcelFileFormat.XLSX);

// Create a new worksheet named "example_sheet"
var sheet = workbook.CreateWorkSheet("example_sheet");

// Set value of a single cell
sheet["A1"].Value = "Example";

// Set value to multiple cells in a range
sheet["A2:A4"].Value = 5;

// Change background color of a cell
sheet["A5"].Style.SetBackgroundColor("#f0f0f0");

// Set style (bold font) to multiple cells in a range
sheet["A5:A6"].Style.Font.Bold = true;

// Set formula for cell A6
sheet["A6"].Value = "=SUM(A2:A4)";

// Verify if the value in A6 is the sum of the range A2:A4
if (sheet["A6"].IntValue == sheet["A2:A4"].IntValue)
{
    Console.WriteLine("Basic test passed");
}

// Save the workbook as "example_workbook.xlsx"
workbook.SaveAs("example_workbook.xlsx");

using IronXL;

// Create a new Excel workbook in XLSX format
WorkBook workbook = WorkBook.Create(ExcelFileFormat.XLSX);

// Create a new worksheet named "example_sheet"
var sheet = workbook.CreateWorkSheet("example_sheet");

// Set value of a single cell
sheet["A1"].Value = "Example";

// Set value to multiple cells in a range
sheet["A2:A4"].Value = 5;

// Change background color of a cell
sheet["A5"].Style.SetBackgroundColor("#f0f0f0");

// Set style (bold font) to multiple cells in a range
sheet["A5:A6"].Style.Font.Bold = true;

// Set formula for cell A6
sheet["A6"].Value = "=SUM(A2:A4)";

// Verify if the value in A6 is the sum of the range A2:A4
if (sheet["A6"].IntValue == sheet["A2:A4"].IntValue)
{
    Console.WriteLine("Basic test passed");
}

// Save the workbook as "example_workbook.xlsx"
workbook.SaveAs("example_workbook.xlsx");

Imports IronXL

' Create a new Excel workbook in XLSX format
Private workbook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)

' Create a new worksheet named "example_sheet"
Private sheet = workbook.CreateWorkSheet("example_sheet")

' Set value of a single cell
Private sheet("A1").Value = "Example"

' Set value to multiple cells in a range
Private sheet("A2:A4").Value = 5

' Change background color of a cell
sheet("A5").Style.SetBackgroundColor("#f0f0f0")

' Set style (bold font) to multiple cells in a range
sheet("A5:A6").Style.Font.Bold = True

' Set formula for cell A6
sheet("A6").Value = "=SUM(A2:A4)"

' Verify if the value in A6 is the sum of the range A2:A4
If sheet("A6").IntValue = sheet("A2:A4").IntValue Then
	Console.WriteLine("Basic test passed")
End If

' Save the workbook as "example_workbook.xlsx"
workbook.SaveAs("example_workbook.xlsx")

In the following code, we import the IronXL library at the top of our program. We then initiate a WorkBook object to create a new Excel workbook in XLSX format. Next, we create a WorkSheet within the WorkBook using the CreateWorkSheet method, providing the worksheet's name as a parameter. It's possible to create multiple worksheets this way. Now, our Excel workbook and worksheet are ready to use.

Next, we enter data into the cells of the Excel worksheet. Cells can be accessed by their names, and the "Value" property is used to access or set cell values. Styles, such as font size and style, can be set for specific cells or ranges of cells. Formulas can also be defined for individual cells or cell ranges. Finally, we save our Excel file as "example_workbook.xlsx", which will be saved to the debug folder of our project.

Output

Here you can see the output of the created program.

Result file displayed in Microsoft Excel

Conclusion

We can create, read and modify existing Microsoft Excel files or an XLSX file in C#. IronXL provides many other features for Microsoft Excel files. You can explore these features from our tutorial page. IronXL is the complete package for working with Excel. IronXL also offers a wide range of features to interact with Excel WorkBook, WorkSheet, and Cells level such as converting between popular formats, cell data formatting, inserting math functions, and even managing charts.

IronXL is entirely free for development. You can use it for free in the development phase with the IronXL watermark. IronXL also offers a free trial key for production, allowing you to test it for 30 days, completely free. IronXL has a reasonable pricing plan that you can purchase at a level that matches your requirements.

IronXL pricing plan

What's more - Iron Software currently offers you five software packages for the price of just two.