Compare documents with GroupDocs.Comparison Leave feedback
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GroupDocs.Comparison finds the differences between two versions of a document and writes a result file with the changes marked up — insertions, deletions and style changes, down to word and character level.
The examples below compare two revisions of the same contract. contract-v1.docx and contract-v2.docx differ in exactly three places: the delivery date, the contract value, and a late-delivery clause added in v2.
The change count comes out higher than three, because GroupDocs.Comparison reports at word level and records a reworded sentence as a deletion plus an insertion rather than as one edit.
The source document goes to the constructor, the revision to Add, and Compare writes the marked-up result.
using GroupDocs.Comparison;
using (Comparer comparer = new Comparer("contract-v1.docx"))
{
comparer.Add("contract-v2.docx");
comparer.Compare("comparison-compare-documents.docx");
}
contract-v1.docx and contract-v2.docx are the sample files used in this example. Download contract-v1.docx and contract-v2.docx.
Binary file (DOCX, 16 KB)
In the result, inserted text is blue, deleted text is red and struck through, and style-only changes are green.
GetChanges returns the differences as data rather than a document, which is what you want when the comparison feeds a review UI or an audit log rather than a human reader.
using System;
using GroupDocs.Comparison;
using GroupDocs.Comparison.Result;
using (Comparer comparer = new Comparer("contract-v1.docx"))
{
comparer.Add("contract-v2.docx");
comparer.Compare();
ChangeInfo[] changes = comparer.GetChanges();
Console.WriteLine("Changes found: " + changes.Length);
foreach (ChangeInfo change in changes)
{
Console.WriteLine(change.Id + ". " + change.Type
+ " | source: '" + change.SourceText + "'"
+ " | target: '" + change.TargetText + "'");
}
}
contract-v1.docx and contract-v2.docx are the sample files used in this example. Download contract-v1.docx and contract-v2.docx.
Changes found: 7
0. Deleted | source: 'The vendor shall deliver the completed remediation plan by 30 June 2026.' | target: 'The vendor shall deliver the completed remediation plan by 31 August 2026.'
1. Inserted | source: 'The vendor shall deliver the completed remediation plan by 30 June 2026.' | target: 'The vendor shall deliver the completed remediation plan by 31 August 2026.'
2. Inserted | source: 'The vendor shall deliver the completed remediation plan by 30 June 2026.' | target: 'The vend
[TRUNCATED]
Each change carries a ComparisonAction. Set it to Reject and re-apply, and the result keeps the source wording for that change while accepting the rest — the API behind a review workflow.
using System;
using GroupDocs.Comparison;
using GroupDocs.Comparison.Result;
using (Comparer comparer = new Comparer("contract-v1.docx"))
{
comparer.Add("contract-v2.docx");
comparer.Compare();
ChangeInfo[] changes = comparer.GetChanges();
// Accept everything except the first change, which we reject
foreach (ChangeInfo change in changes)
{
change.ComparisonAction = ComparisonAction.Accept;
}
if (changes.Length > 0)
{
changes[0].ComparisonAction = ComparisonAction.Reject;
Console.WriteLine("Rejected: '" + changes[0].TargetText + "'");
}
comparer.ApplyChanges("comparison-accept-reject.docx", new ApplyChangeOptions
{
Changes = changes
});
}
contract-v1.docx and contract-v2.docx are the sample files used in this example. Download contract-v1.docx and contract-v2.docx.
Binary file (DOCX, 16 KB)
GroupDocs.Comparison also compares more than two revisions at once, compares whole directories, produces a summary page, compares password-protected documents, and lets you tune sensitivity and the styling of each change type.
- GroupDocs.Comparison for .NET documentation — the full product guide
- Supported file formats
- API reference
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