programmatically comparing word documents

You should use Document class to compare files and open in a Word document the result.

using OfficeWord = Microsoft.Office.Interop.Word; object fileToOpen = (object)@"D:\doc1.docx"; string fileToCompare = @"D:\doc2.docx"; var app = Global.OfficeFile.WordApp; object readOnly = false; object AddToRecent = false; object Visible = false; OfficeWord.Document docZero = app.Documents.Open(fileToOpen, ref missing, ref readOnly, ref AddToRecent, Visible: ref Visible); docZero.Final = false; docZero.TrackRevisions = true; docZero.ShowRevisions = true; docZero.PrintRevisions = true; //the OfficeWord.WdCompareTargetNew defines a new file, you can change this valid value to change how word will open the document docZero.Compare(fileToCompare, missing, OfficeWord.WdCompareTarget.wdCompareTargetNew, true, false, false, false, false); 

So my requirements were that I had to use a .Net lib and I wanted to avoid working on actual files but work with streams.

ZipArchive is in System.IO.Compressed

What I did and it worked out quite nicely was using the ZipArchive from .Net and comparing contents while skipping the .rels file because it seems the it is randomly generated on each file creation. Here's my snippet:

 private static bool AreWordFilesSame(byte[] wordA, byte[] wordB) { using (var streamA = new MemoryStream(wordA)) using (var streamB = new MemoryStream(wordB)) using (var zipA = new ZipArchive(streamA)) using (var zipB = new ZipArchive(streamB)) { streamA.Seek(0, SeekOrigin.Begin); streamB.Seek(0, SeekOrigin.Begin); for(int i = 0; i < zipA.Entries.Count; ++i) { Assert.AreEqual(zipA.Entries[i].Name, zipB.Entries[i].Name); if (zipA.Entries[i].Name.EndsWith(".rels")) //These are some weird word files with autogenerated hashes { continue; } var streamFromA = zipA.Entries[i].Open(); var streamFromB = zipB.Entries[i].Open(); using (var readerA = new StreamReader(streamFromA)) using (var readerB = new StreamReader(streamFromB)) { var bytesA = readerA.ReadToEnd(); var bytesB = readerB.ReadToEnd(); if (bytesA != bytesB || bytesA.Length == 0) { return false; } } } return true; } } 

This function lets you compare two documents as well as two versions of a document in C#.

public async Task<object> compare() { Word.Application wordApp = new Word.Application(); wordApp.Visible = false; object wordTrue = (object)true; object wordFalse = (object)false; object fileToOpen = @"Give your file path here"; object missing = Type.Missing; Word.Document doc1 = wordApp.Documents.Open(ref fileToOpen, ref missing, ref wordFalse, ref wordFalse, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref wordTrue, ref missing, ref missing, ref missing, ref missing); object fileToOpen1 = @"Give your file path here"; Word.Document doc2 = wordApp.Documents.Open(ref fileToOpen1, ref missing, ref wordFalse, ref wordFalse, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing); Word.Document doc = wordApp.CompareDocuments(doc1, doc2, Word.WdCompareDestination.wdCompareDestinationNew, Word.WdGranularity.wdGranularityWordLevel, true, true, true, true, true, true, true, true, true, true, "", true); doc1.Close(ref missing, ref missing, ref missing); doc2.Close(ref missing, ref missing, ref missing); // This Hides both original and revised documents you can change it according to your use case. wordApp.ActiveWindow.ShowSourceDocuments = WdShowSourceDocuments.wdShowSourceDocumentsNone; wordApp.Visible = true; doc.Activate(); return Ok("Compared Successfully"); } 

For a solution on a server, or running without an installation of Word and using the COM tools, you could use the WmlComparer component of XmlPowerTools.

The documentation is a bit limited, but here's an example usage:

var expected = File.ReadAllBytes(@"c:\expected.docx"); var actual = File.ReadAllBytes(@"c:\result.docx"); var expectedresult = new WmlDocument("expected.docx", expected); var actualDocument = new WmlDocument("result.docx", actual); var comparisonSettings = new WmlComparerSettings(); var comparisonResults = WmlComparer.Compare(expectedresult, actualDocument, comparisonSettings); var revisions = WmlComparer.GetRevisions(comparisonResults, comparisonSettings); 

which will show you the differences between the two documents.

You should really be extracting the doc into a string and diff'ing that.

You only care about the textual changes and not the formatting right?

To do a comparison between Word documents, you need

1. A library to manipulate Word document, e.g. read paragraphs, text, tables etc from a Word file. You can try Office Interop, OpenXML or Aspose.Words for .NET.
2. An algorithm/library to do the actual comparison, on the text retrieved from both Word documents. You can write your own or use a library like DiffMatchPatch or similar.

This question is old, now there are more solutions like GroupDocs Compare available.

Document Comparison by Aspose.Words for .NET is an open source showcase project that uses Aspose.Words and DiffMatchPatch for comparison.

I work at Aspose as a Developer Evangelist.