C# Save to CSV Using IronXL

Introduction to Comma Separated Values

A Comma Separated Values (CSV) file is one of the most widely used formats for storing and exchanging tabular data between different applications. In its simplest form, a CSV file is a plain text file where each line contains a series of values separated by commas. This straightforward structure makes CSV data easy to generate, read, and process across a wide range of software systems. The CSV format is both lightweight and human-readable, which is why it’s a popular choice for exporting reports, transferring data between databases, and integrating with analytics tools.

Understanding CSV Format

The CSV format is designed for simplicity: each line in a CSV file represents a single record, and each value within that line is separated by a comma. The first line of the file usually serves as the header, listing the names of each column. Every subsequent line contains the actual data, with each value corresponding to a column in the header. This structure allows CSV files to represent complex tables of data in a format that is both easy to read and easy to parse.

How Do I Install IronXL in My Project?

Adding IronXL to a new project takes just a few seconds through NuGet packages, Microsoft's package manager for .NET. Open Visual Studio, then access the NuGet Package Manager Console and run the following command:

Install-Package IronXL.Excel

Alternatively, right-click on your project in Solution Explorer, select "Manage NuGet Packages," search for "IronXL" in the Browse tab, and click Install. IronXL supports .NET Framework 4.6.2+, .NET Core, .NET 5/6/7/8, and runs on any platform without external dependencies or COM interop requirements.

Once installed, add the IronXL namespace to your code file using the using statement:

using IronXL;

using IronXL;

Imports IronXL

This single namespace provides access to all the classes needed for spreadsheet creation and CSV export operations. Unlike approaches that rely on StreamWriter class or StringBuilder for writing CSV files manually, IronXL handles all the complexity of proper CSV formatting automatically.

How Do I Create a New CSV File from Scratch?

Creating a new CSV file programmatically involves three straightforward steps: creating a workbook, populating it with data, and saving it in CSV format. IronXL's intuitive API mirrors the familiar Excel object model, making it easy for developers to write code that works with spreadsheet concepts in a console application or any .NET project type.

Consider a scenario where you need to export a list of employee objects to CSV. Here's a complete example showing how to write CSV data:

using IronXL;
class Program
{
 public static void Main(string[] args)
 {
  // Create a new workbook and worksheet
  WorkBook workBook = WorkBook.Create();
  WorkSheet sheet = workBook.CreateWorkSheet("Employees");
  // Add header row with column names
  sheet["A1"].Value = "EmployeeID";
  sheet["B1"].Value = "Name";
  sheet["C1"].Value = "Department";
  sheet["D1"].Value = "Salary";
  // Add employee data rows
  sheet["A2"].Value = 1001;
  sheet["B2"].Value = "Sarah Johnson";
  sheet["C2"].Value = "Engineering";
  sheet["D2"].Value = 85000;
  sheet["A3"].Value = 1002;
  sheet["B3"].Value = "Michael Chen";
  sheet["C3"].Value = "Marketing";
  sheet["D3"].Value = 72000;
  sheet["A4"].Value = 1003;
  sheet["B4"].Value = "Emily Rodriguez";
  sheet["C4"].Value = "Finance";
  sheet["D4"].Value = 91000;
  // Save as CSV file - output goes to the specified path
  workBook.SaveAsCsv("employees.csv", ",");
 }
}

using IronXL;
class Program
{
 public static void Main(string[] args)
 {
  // Create a new workbook and worksheet
  WorkBook workBook = WorkBook.Create();
  WorkSheet sheet = workBook.CreateWorkSheet("Employees");
  // Add header row with column names
  sheet["A1"].Value = "EmployeeID";
  sheet["B1"].Value = "Name";
  sheet["C1"].Value = "Department";
  sheet["D1"].Value = "Salary";
  // Add employee data rows
  sheet["A2"].Value = 1001;
  sheet["B2"].Value = "Sarah Johnson";
  sheet["C2"].Value = "Engineering";
  sheet["D2"].Value = 85000;
  sheet["A3"].Value = 1002;
  sheet["B3"].Value = "Michael Chen";
  sheet["C3"].Value = "Marketing";
  sheet["D3"].Value = 72000;
  sheet["A4"].Value = 1003;
  sheet["B4"].Value = "Emily Rodriguez";
  sheet["C4"].Value = "Finance";
  sheet["D4"].Value = 91000;
  // Save as CSV file - output goes to the specified path
  workBook.SaveAsCsv("employees.csv", ",");
 }
}

IRON VB CONVERTER ERROR developers@ironsoftware.com

The WorkBook.Create() method initializes a new spreadsheet entirely in memory, requiring no temporary files or disk I/O until the final save operation. The CreateWorkSheet() method adds a named worksheet to the workbook—this name becomes relevant when exporting multi-sheet workbooks to CSV later.

using IronXL;
// Define the Student class with public string properties
public class Student
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
}
// In your program class or method
var students = new List<Student>
{
    new Student { FirstName = "John", LastName = "Smith", Email = "john@example.com" },
    new Student { FirstName = "Jane", LastName = "Doe", Email = "jane@example.com" }
};
WorkBook workBook = WorkBook.Create();
WorkSheet sheet = workBook.DefaultWorkSheet;
// Add header row
sheet["A1"].Value = "FirstName";
sheet["B1"].Value = "LastName";
sheet["C1"].Value = "Email";
// Use foreach to iterate through the list and write each item
int row = 2;
foreach (var item in students)
{
    sheet[$"A{row}"].Value = item.FirstName;
    sheet[$"B{row}"].Value = item.LastName;
    sheet[$"C{row}"].Value = item.Email;
    row++;
}
workBook.SaveAsCsv("students.csv", ",");

using IronXL;
// Define the Student class with public string properties
public class Student
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
}
// In your program class or method
var students = new List<Student>
{
    new Student { FirstName = "John", LastName = "Smith", Email = "john@example.com" },
    new Student { FirstName = "Jane", LastName = "Doe", Email = "jane@example.com" }
};
WorkBook workBook = WorkBook.Create();
WorkSheet sheet = workBook.DefaultWorkSheet;
// Add header row
sheet["A1"].Value = "FirstName";
sheet["B1"].Value = "LastName";
sheet["C1"].Value = "Email";
// Use foreach to iterate through the list and write each item
int row = 2;
foreach (var item in students)
{
    sheet[$"A{row}"].Value = item.FirstName;
    sheet[$"B{row}"].Value = item.LastName;
    sheet[$"C{row}"].Value = item.Email;
    row++;
}
workBook.SaveAsCsv("students.csv", ",");

IRON VB CONVERTER ERROR developers@ironsoftware.com

How Do I Convert an Existing Excel File to CSV?

Converting Excel spreadsheets to CSV format is a common requirement when integrating with legacy systems, preparing data for database imports, or generating machine-readable output from human-created reports. IronXL handles this conversion with minimal code while preserving data accuracy. The file exists on disk and can be loaded directly.

using IronXL;

// Load an existing Excel file from the specified location
WorkBook workBook = WorkBook.Load("Monthly_Report_20251012.xlsx");

// Convert and save as CSV format
workBook.SaveAsCsv("Monthly_Report_20251012.csv");

using IronXL;

// Load an existing Excel file from the specified location
WorkBook workBook = WorkBook.Load("Monthly_Report_20251012.xlsx");

// Convert and save as CSV format
workBook.SaveAsCsv("Monthly_Report_20251012.csv");

IRON VB CONVERTER ERROR developers@ironsoftware.com

The Load() method opens Excel files in various formats including XLSX, XLS, XLSM, and even existing CSV or TSV files. This flexibility means developers can build standardized export pipelines that accept input files regardless of their original format. The system handles the file operations internally.

using IronXL;

// Load a multi-sheet workbook (e.g., annual sales by region)
WorkBook workBook = WorkBook.Load("annual_sales.xlsx");

// Export all sheets to CSV - creates separate files for each
workBook.SaveAsCsv("sales_export.csv");
// Output: sales_export.North.csv, sales_export.South.csv, sales_export.East.csv, etc.

// Or export a specific worksheet
WorkSheet northRegion = workBook.GetWorkSheet("North");
northRegion.SaveAsCsv("north_region_sales.csv");

using IronXL;

// Load a multi-sheet workbook (e.g., annual sales by region)
WorkBook workBook = WorkBook.Load("annual_sales.xlsx");

// Export all sheets to CSV - creates separate files for each
workBook.SaveAsCsv("sales_export.csv");
// Output: sales_export.North.csv, sales_export.South.csv, sales_export.East.csv, etc.

// Or export a specific worksheet
WorkSheet northRegion = workBook.GetWorkSheet("North");
northRegion.SaveAsCsv("north_region_sales.csv");

IRON VB CONVERTER ERROR developers@ironsoftware.com

How Do I Export a DataTable to CSV?

Enterprise applications frequently work with DataTable objects populated from database queries, API responses, or in-memory data processing. IronXL bridges the gap between these .NET data structures and file exports, providing a reliable path from application memory to shareable CSV files. This method is more robust than manually writing CSV files with a var writer approach or using a new StreamWriter.

using IronXL;
using System.Data;

// Create and populate a DataTable with columns
DataTable products = new DataTable();
products.Columns.Add("SKU", typeof(string));
products.Columns.Add("ProductName", typeof(string));
products.Columns.Add("Price", typeof(decimal));
products.Columns.Add("InStock", typeof(int));

// Add rows of data
products.Rows.Add("SKU-001", "Wireless Mouse", 29.99m, 150);
products.Rows.Add("SKU-002", "Mechanical Keyboard", 89.99m, 75);
products.Rows.Add("SKU-003", "USB-C Hub", 45.99m, 200);

// Create workbook and transfer DataTable contents
WorkBook workBook = WorkBook.Create();
WorkSheet sheet = workBook.DefaultWorkSheet;

// Add header row from column names
for (int col = 0; col < products.Columns.Count; col++)
{
    sheet.SetCellValue(0, col, products.Columns[col].ColumnName);
}

// Add data rows using a loop
for (int row = 0; row < products.Rows.Count; row++)
{
    for (int col = 0; col < products.Columns.Count; col++)
    {
        sheet.SetCellValue(row + 1, col, products.Rows[row][col].ToString());
    }
}

// Export to CSV and save to the specified path
workBook.SaveAsCsv("product_inventory.csv", ",");

using IronXL;
using System.Data;

// Create and populate a DataTable with columns
DataTable products = new DataTable();
products.Columns.Add("SKU", typeof(string));
products.Columns.Add("ProductName", typeof(string));
products.Columns.Add("Price", typeof(decimal));
products.Columns.Add("InStock", typeof(int));

// Add rows of data
products.Rows.Add("SKU-001", "Wireless Mouse", 29.99m, 150);
products.Rows.Add("SKU-002", "Mechanical Keyboard", 89.99m, 75);
products.Rows.Add("SKU-003", "USB-C Hub", 45.99m, 200);

// Create workbook and transfer DataTable contents
WorkBook workBook = WorkBook.Create();
WorkSheet sheet = workBook.DefaultWorkSheet;

// Add header row from column names
for (int col = 0; col < products.Columns.Count; col++)
{
    sheet.SetCellValue(0, col, products.Columns[col].ColumnName);
}

// Add data rows using a loop
for (int row = 0; row < products.Rows.Count; row++)
{
    for (int col = 0; col < products.Columns.Count; col++)
    {
        sheet.SetCellValue(row + 1, col, products.Rows[row][col].ToString());
    }
}

// Export to CSV and save to the specified path
workBook.SaveAsCsv("product_inventory.csv", ",");

IRON VB CONVERTER ERROR developers@ironsoftware.com

This pattern iterates through the DataTable structure, transferring column headers first and then populating each data row systematically. The DefaultWorkSheet property provides quick access to the first worksheet in a newly created workbook, eliminating the need for explicit worksheet creation in simple scenarios. By default, the method processes all rows in sequence.

How Do I Handle Custom Delimiters in CSV Files?

Different systems and regional standards require varying delimiter characters. While the comma is the standard separator in many countries, semicolons are often preferred in European regions where commas serve as decimal separators in numeric values. Tab-separated files (TSV) are popular when source data contains commas within field values. IronXL's SaveAsCsv() method accommodates all these scenarios without requiring additional code to handle each line of output.

using IronXL;
WorkBook workBook = WorkBook.Load("data.xlsx");
// Standard comma delimiter (default format)
workBook.SaveAsCsv("output_comma.csv", ",");
// Semicolon delimiter (common in European systems)
workBook.SaveAsCsv("output_semicolon.csv", ";");
// Tab delimiter (TSV format)
workBook.SaveAsCsv("output_tab.tsv", "\t");
// Pipe delimiter (used in some data interchange formats)
workBook.SaveAsCsv("output_pipe.csv", "|");

using IronXL;
WorkBook workBook = WorkBook.Load("data.xlsx");
// Standard comma delimiter (default format)
workBook.SaveAsCsv("output_comma.csv", ",");
// Semicolon delimiter (common in European systems)
workBook.SaveAsCsv("output_semicolon.csv", ";");
// Tab delimiter (TSV format)
workBook.SaveAsCsv("output_tab.tsv", "\t");
// Pipe delimiter (used in some data interchange formats)
workBook.SaveAsCsv("output_pipe.csv", "|");

IRON VB CONVERTER ERROR developers@ironsoftware.com

The second parameter of SaveAsCsv() accepts any string as the delimiter, providing complete flexibility for integration with diverse systems and regional requirements. When generating files for international distribution, consider the target system's locale expectations—European financial systems often expect semicolon separation, while North American systems typically default to commas.

Best Practices

When working with CSV files in C#, following best practices ensures your data remains accurate, readable, and compatible with other systems. Here are some essential guidelines:

• Consistent Delimiters: Always use a consistent delimiter, such as a comma or semicolon, throughout your CSV file. This helps prevent parsing errors when importing or exporting data.
• Quoting Special Values: If your data values contain commas, quotes, or other special characters, enclose them in double quotes to maintain the integrity of your CSV data.
• Date and Time Formats: Use a consistent date and time format across your CSV files to avoid confusion and ensure compatibility with other applications.
• Avoid Newlines in Values: Refrain from including newline characters within values, as these can disrupt the row structure and cause formatting issues.
• Leverage Libraries: Utilize libraries like CsvHelper to simplify reading and writing CSV files. CsvHelper handles many of the complexities of the CSV format, such as escaping, quoting, and custom delimiters.
• File Handling: Always check if the file exists before writing, and handle exceptions gracefully. Use the using statement to ensure that file streams are properly closed and disposed of after use.

For example, you can start a new project in Visual Studio, install the CsvHelper NuGet package, and use the CsvWriter class to write data to a CSV file. Define a Student class with properties like Firstname and Lastname, then export a list of Student objects to a CSV file using CsvWriter. This approach not only streamlines your workflow but also reduces the risk of errors, ensuring your CSV files are well-structured and ready for use in any application.

Conclusion

Creating and exporting CSV files in C# becomes remarkably efficient with IronXL. From generating new files populated with structured data to converting complex multi-sheet Excel workbooks, the library provides a clean, intuitive API that handles the underlying complexity of proper CSV formatting, special character escaping, and formula evaluation. Unlike manual approaches that require writing custom code with var stream and var csv variables or append text logic, IronXL streamlines the entire process.

The key methods and techniques covered in this post include:

• WorkBook.Create() for initializing new spreadsheets in memory
• WorkBook.Load() for opening existing Excel files in any supported format
• SaveAsCsv() for exporting data with customizable delimiters
• Individual worksheet export using GetWorkSheet() for targeted conversions
• DataTable iteration patterns for database-to-CSV workflows
• Object list export using foreach loops

Start your free trial to explore the full range of spreadsheet capabilities, or purchase a license for production deployment. For additional examples covering advanced scenarios like cell styling, formula creation, and chart generation, explore the comprehensive IronXL documentation and code examples library.