IronXL How-Tos Load Spreadsheets How to Load Existing Spreadsheets ByChaknith Bin October 15, 2023 Updated June 22, 2025 Share: CSV (Comma-Separated Values) file format is for tabular data where values are separated by commas, commonly used for data exchange. On the other hand, TSV (Tab-Separated Values) uses tabs to separate values, preferred when data contains commas.The DataSet class in Microsoft's .NET is a part of the ADO.NET (ActiveX Data Objects for .NET) technology. It's often used in database-related applications and allows you to work with data from various sources like databases, XML, and more.Data contained in Excel file formats such as XLSX, XLS, XLSM, XLTX, CSV, and TSV as well as a DataSet object can be loaded into an Excel spreadsheet using IronXL. View the IronXL YouTube Playlist How to Load Existing Spreadsheets Download the C# library to load spreadsheet Prepare the file or data object to be loaded into the spreadsheet Use the Load method to load the data into a workbook object Use the LoadWorkSheetsFromDataSet method to load data from a DataSet object Export the workbook as an Excel file Get started with IronXL Start using IronXL in your project today with a free trial. First Step: Start for Free Load Spreadsheet Example Use the static method Load to load an existing Excel workbook. The method supports XLSX, XLS, XLSM, XLTX, CSV, and TSV file formats. In cases where the workbook is protected with a password, you can pass the password as the second parameter to the method. The method also accepts workbook data in the form of a byte array or a stream, where the dedicated FromByteArray and FromStream methods can be used, respectively. :path=/static-assets/excel/content-code-examples/how-to/load-spreadsheet-load-spreadsheet.cs using IronXL; // Import the IronXL library for working with Excel files. // Instead of loading the workbook without error handling, wrap it in a try-catch block for safety. try { // Load an Excel workbook from a file. The IronXL library supports various file formats including XLSX, XLS, XLSM, XLTX, CSV, and TSV. WorkBook workBook = WorkBook.Load("sample.xlsx"); // At this point, 'workBook' is an instance of the loaded workbook. // You can now proceed to manipulate the workbook, such as accessing worksheets, reading data, etc. // Example: Accessing the first worksheet WorkSheet sheet = workBook.WorkSheets.First(); // You might want to perform operations like iterating over rows, reading cell values, etc. // Example: Reading a value from a specific cell string cellValue = sheet["A1"].Text; // Optionally, output the value from the specified cell to confirm reading was successful Console.WriteLine($"The value in cell A1 is: {cellValue}"); } catch (Exception ex) { // It's a good practice to handle exceptions in case the workbook file doesn't exist or there's an issue with reading it. Console.WriteLine($"An error occurred while loading or processing the workbook: {ex.Message}"); } Imports IronXL ' Import the IronXL library for working with Excel files. ' Instead of loading the workbook without error handling, wrap it in a try-catch block for safety. Try ' Load an Excel workbook from a file. The IronXL library supports various file formats including XLSX, XLS, XLSM, XLTX, CSV, and TSV. Dim workBook As WorkBook = WorkBook.Load("sample.xlsx") ' At this point, 'workBook' is an instance of the loaded workbook. ' You can now proceed to manipulate the workbook, such as accessing worksheets, reading data, etc. ' Example: Accessing the first worksheet Dim sheet As WorkSheet = workBook.WorkSheets.First() ' You might want to perform operations like iterating over rows, reading cell values, etc. ' Example: Reading a value from a specific cell Dim cellValue As String = sheet("A1").Text ' Optionally, output the value from the specified cell to confirm reading was successful Console.WriteLine($"The value in cell A1 is: {cellValue}") Catch ex As Exception ' It's a good practice to handle exceptions in case the workbook file doesn't exist or there's an issue with reading it. Console.WriteLine($"An error occurred while loading or processing the workbook: {ex.Message}") End Try $vbLabelText $csharpLabel Load CSV file While the Load method can read all available file formats, it is recommended to use the LoadCSV method specifically for CSV file formats for optimal handling. :path=/static-assets/excel/content-code-examples/how-to/load-spreadsheet-load-csv.cs using IronXL; // This code demonstrates how to load a CSV file using the IronXL library. // IronXL must be installed via NuGet package manager in your project to work with WorkBook class. // Load a CSV file into a WorkBook object. The path to the CSV file is specified as "sample.csv". // Ensure "sample.csv" is present in the project directory or provide the correct path to the file. WorkBook workBook = WorkBook.LoadCSV("sample.csv"); // At this point, the CSV file is loaded into the `workBook` object. // You can now perform various operations on the loaded data, such as reading or modifying cell values. Imports IronXL ' This code demonstrates how to load a CSV file using the IronXL library. ' IronXL must be installed via NuGet package manager in your project to work with WorkBook class. ' Load a CSV file into a WorkBook object. The path to the CSV file is specified as "sample.csv". ' Ensure "sample.csv" is present in the project directory or provide the correct path to the file. Private workBook As WorkBook = WorkBook.LoadCSV("sample.csv") ' At this point, the CSV file is loaded into the `workBook` object. ' You can now perform various operations on the loaded data, such as reading or modifying cell values. $vbLabelText $csharpLabel Load DataSet The DataSet class in Microsoft .NET is used for managing and working with data in a disconnected, in-memory representation. This DataSet can also be loaded into the workbook using the LoadWorkSheetsFromDataSet method. In the code example below, an empty DataSet is created; however, it's more common to instantiate the DataSet from a database query. :path=/static-assets/excel/content-code-examples/how-to/load-spreadsheet-load-dataset.cs using IronXL; using System.Data; // This code demonstrates how to create an Excel workbook from a DataSet using IronXL, // a .NET library for working with Excel files. // Create a new DataSet to hold data tables, which provides in-memory data storage. DataSet dataSet = new DataSet(); // Example of adding a DataTable to the DataSet for demonstration. // In an actual implementation, populate the DataSet with real data tables. DataTable table = new DataTable("SampleTable"); dataSet.Tables.Add(table); // Create a new WorkBook using IronXL. This will represent an Excel workbook. WorkBook workBook = WorkBook.Create(ExcelFileFormat.XLSX); // Load worksheets into the WorkBook from the DataSet. // Each DataTable in the DataSet will result in a new worksheet in the WorkBook. workBook.LoadWorkSheetsFromDataSet(dataSet); // Add comments to clarify: // - If the DataSet is empty, the WorkBook will be created without any worksheets. // - Ensure that the DataSet is populated with one or more tables to have data reflected in the workbook. Imports IronXL Imports System.Data ' This code demonstrates how to create an Excel workbook from a DataSet using IronXL, ' a .NET library for working with Excel files. ' Create a new DataSet to hold data tables, which provides in-memory data storage. Private dataSet As New DataSet() ' Example of adding a DataTable to the DataSet for demonstration. ' In an actual implementation, populate the DataSet with real data tables. Private table As New DataTable("SampleTable") dataSet.Tables.Add(table) ' Create a new WorkBook using IronXL. This will represent an Excel workbook. Dim workBook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX) ' Load worksheets into the WorkBook from the DataSet. ' Each DataTable in the DataSet will result in a new worksheet in the WorkBook. workBook.LoadWorkSheetsFromDataSet(dataSet) ' Add comments to clarify: ' - If the DataSet is empty, the WorkBook will be created without any worksheets. ' - Ensure that the DataSet is populated with one or more tables to have data reflected in the workbook. $vbLabelText $csharpLabel Frequently Asked Questions What file formats can be loaded using this library? IronXL supports loading XLSX, XLS, XLSM, XLTX, CSV, and TSV file formats. How can I load a password-protected Excel workbook? To load a password-protected Excel workbook using IronXL, use the Load method and pass the password as the second parameter. Can this library load data directly from a byte array or stream? Yes, IronXL can load workbook data from a byte array using the LoadFromByteArray method and from a stream using the LoadFromStream method. What is the recommended method for loading CSV files? While the Load method can read CSV files, it is recommended to use the LoadCSV method for optimal handling of CSV file formats with IronXL. How does this library handle loading data from a DataSet object? IronXL can load data from a DataSet object using the LoadWorkSheetsFromDataSet method, creating one worksheet per DataTable in the DataSet. What is the purpose of the DataSet class in .NET? The DataSet class in .NET is used for managing and working with data in a disconnected, in-memory representation, typically filled from database queries. How can I get started with using this library to load spreadsheets? To get started with IronXL, download the C# library from NuGet, prepare your file or data object, and use the Load method to load the data into a workbook object. Chaknith Bin Chat with engineering team now Software Engineer Chaknith is the Sherlock Holmes of developers. It first occurred to him he might have a future in software engineering, when he was doing code challenges for fun. His focus is on IronXL and IronBarcode, but he takes pride in helping customers with every product. Chaknith leverages his knowledge from talking directly with customers, to help further improve the products themselves. His anecdotal feedback goes beyond Jira tickets and supports product development, documentation and marketing, to improve customer’s overall experience.When he isn’t in the office, he can be found learning about machine learning, coding and hiking. Ready to Get Started? Start Free Trial Total downloads: 1,446,926 View Licenses >