Use C to extract all text in PDF files (support.Net core)

PDF yes Portable Document Format For short , Meaning for “ Portable document format ”, By Adobe Systems Used with applications 、 operating system 、 The file format developed by the file exchange in a hardware independent way .PDF Document to PostScript Language is based on image model , No matter in which kind of printer can guarantee the accurate color and accurate printing effect , namely PDF Will faithfully reproduce every character of the original 、 Color and image .

Whereas PDF The file format is complex , Generally, third-party components are used to PDF To operate , This article USES itext7 .

Official website ：https://itextpdf.com/

NuGet：https://www.nuget.org/packages/itext7/

adopt NuGet introduce itext7 After component , You can use the following code to extract PDF The text in the document ：

using System.Collections.Generic;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Canvas.Parser;
using iText.Kernel.Pdf.Canvas.Parser.Listener;
public static class PdfHelper
{
    public static IEnumerable<string> ExtractText(string filename)
    {
        using (var r = new PdfReader(filename))
        using (var doc = new PdfDocument(r))
        {
            for (int i = 1; i < doc.GetNumberOfPages(); i++)
            {
                ITextExtractionStrategy strategy = new LocationTextExtractionStrategy();
                string text = PdfTextExtractor.GetTextFromPage(doc.GetPage(i), strategy);
                yield return text;
            }
        }
    }
}

Sample code ：

var lines = PdfHelper.ExtractText("{PDF File path }").ToList();

It should be noted that ： If your PDF The document is a scanned version based on pictures , Then the code in this article cannot extract text , What you need is OCR technology .