Convert Excel to PDF in C: Easy Guide

In the world of document management and data sharing, converting Excel spreadsheets to PDF format is an essential skill. PDF files are universally accepted, maintain document integrity, and are ideal for printing. This guide is crafted to provide developers with a straightforward approach to transform Excel files into PDF documents using C# programming language.

Why Convert Excel to PDF?

The transition from Excel to PDF comes with several advantages:

• Portability: PDFs can be opened on any device without special software.
• Security: PDFs can be password-protected to prevent unauthorized edits.
• Unchangeability: Once saved, the data format and layout remain fixed.
• Better for Sharing: PDF documents preserve the structure and appearance of Excel sheets, making them easier to review and comment on.

Prerequisites for Conversion

To proceed with converting Excel to PDF in C#, you need:

• Microsoft Excel or a compatible software installed on your machine.
• .NET Framework or .NET Core environment.
• A C# IDE like Visual Studio.
• The Interop.Excel library or a third-party component like EPPlus or NPOI.

Choosing the Right Library

There are a few libraries you can use:

• Microsoft.Office.Interop.Excel: A built-in library for interacting with Excel through COM objects, which is not available on non-Windows platforms.
• EPPlus: An open-source library for reading and writing Excel 2007/2010/2013/2016 files, without requiring Microsoft Excel on the server.
• NPOI: Another open-source solution for creating and manipulating Office documents, including Excel files.

Steps to Convert Excel to PDF

Using Microsoft.Office.Interop.Excel

Here’s how you can convert an Excel file to PDF using Interop:

using Excel = Microsoft.Office.Interop.Excel;

public void ConvertToPDF(string excelFilePath, string pdfFilePath)
{
    Excel.Application excel = new Excel.Application();
    Excel.Workbook workbook = excel.Workbooks.Open(excelFilePath);
    workbook.ExportAsFixedFormat(Excel.XlFixedFormatType.xlTypePDF, pdfFilePath);
    workbook.Close();
    excel.Quit();
    Marshal.ReleaseComObject(workbook);
    Marshal.ReleaseComObject(excel);
}

⚠️ Note: Remember to release COM objects to avoid memory leaks.

Using EPPlus

EPPlus doesn’t natively convert to PDF, but you can combine it with the SaveFileDialog or a similar approach:

using OfficeOpenXml;
using System.IO;

public void ConvertToPDF(string excelFilePath, string pdfFilePath)
{
    using (var package = new ExcelPackage(new FileInfo(excelFilePath)))
    {
        var worksheet = package.Workbook.Worksheets[1];
        using (var memoryStream = new MemoryStream())
        {
            package.SaveAs(memoryStream);
            memoryStream.Seek(0, SeekOrigin.Begin);
            var document = Spire.Pdf.PdfDocument.FromStream(memoryStream);
            document.Save(pdfFilePath, Spire.Pdf.FileFormat.PDF);
        }
    }
}

📌 Note: EPPlus requires a PDF conversion component like Spire.PDF.

Using NPOI

Similar to EPPlus, NPOI can be combined with PDF generation libraries:

using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using Spire.Pdf;
using System.IO;

public void ConvertToPDF(string excelFilePath, string pdfFilePath)
{
    using (FileStream file = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read))
    {
        IWorkbook workbook = new XSSFWorkbook(file);
        ISheet sheet = workbook.GetSheetAt(0);
        
        using (var memoryStream = new MemoryStream())
        {
            workbook.Write(memoryStream);
            memoryStream.Seek(0, SeekOrigin.Begin);
            PdfDocument pdf = new PdfDocument();
            PdfSection section = pdf.Sections.Add();
            PdfPageBase page = section.Pages.Add();
            PdfTable table = AddExcelToPdf(page, sheet);
            pdf.SaveToFile(pdfFilePath, FileFormat.PDF);
        }
    }
}

private PdfTable AddExcelToPdf(PdfPageBase page, ISheet sheet)
{
    // Implementation to add Excel data as a table to the PDF page
}

⚠️ Note: This method involves creating a PDF manually with the Excel data.

Optimizing the Conversion Process

To improve efficiency:

• Use async/await if your application supports asynchronous operations.
• If dealing with large files, consider memory management to prevent overflow.
• Batch processing can be applied for multiple file conversions.

💡 Note: For large files, you might need to adjust Excel application settings for better performance.

In summary, converting Excel files to PDF programmatically using C# involves choosing the right library for your needs, implementing the conversion logic, and ensuring that memory and resources are managed correctly. Whether you're archiving data, sharing reports, or ensuring document integrity, mastering this process will significantly enhance your document management capabilities. By following these steps and keeping in mind the notes for each method, you'll be equipped to handle various scenarios of Excel to PDF conversion with ease.

Why should I convert Excel to PDF?

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Converting Excel files to PDF ensures that the document remains unaltered when shared, protects data integrity, and makes it easier to distribute files across different systems without compatibility issues.

Can I convert Excel files to PDF without Microsoft Excel installed?

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Yes, using libraries like EPPlus or NPOI, you can convert Excel files to PDF even if Microsoft Excel isn’t installed on your machine. You’ll need an additional PDF conversion library like Spire.PDF for this approach.

How do I handle password-protected Excel files during conversion?

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If your Excel file is password-protected, you’ll need to supply the password when opening the workbook. This can be done programmatically by passing the password to the appropriate method of the library you are using, like Workbook.Open(string, string).