Skip to end of metadata
Go to start of metadata
Contents Summary

Sometimes it is necessary to determine the format of a document before opening because the file extension does not guarantee that the contents of the file are appropriate. For example, it is known that Crystal Reports often outputs documents in RTF format, but gives them the .doc extension.

Aspose.Words provides an ability to obtain information about the file type in order to avoid an exception if you are not sure what the actual content of the file is.

Detect File Format without an Exception

When you are dealing with multiple documents in various file formats, you may need to separate out those files that can be processed by Aspose.Words from those that cannot. You may also want to know why some of the documents cannot be processed.

If you attempt to load a file into a Document object and Aspose.Words cannot recognize the file format or the format is not supported, Aspose.Words will throw an exception. You can catch those exceptions and analyze them, but Aspose.Words also provides the DetectFileFormat method that allows us to quickly determine the file format without loading a document with possible exceptions. This method returns a FileFormatInfo object that contains the detected information about the file type.

DetectFileFormat only checks the file format but does not validate the file format. There is no guarantee that the file will be opened successfully, even if DetectFileFormat returns that it is one of the supported formats. This is because of DetectFileFormat method reads only partial file format data, sufficient for checking the file format, but not enough for complete validation.

Check Files Format Compatibility

We can check the format compatibility of all files in the selected folder and sort them by format into corresponding subfolders.

Since we are dealing with contents in a folder, the first thing we need to do is get a collection of all the files in this folder using the GetFiles method of the Directory class (from the System.IO namespace).

The following code example shows how to get a list of all the files in the folder:

When all the files are collected, the rest of the work is done by the DetectFileFormat method, which checks the file format.

The following code example shows how to iterate over the collected list of files, check the format of each file, and moves each file to the appropriate folder:

The files are moved into appropriate subfolders using the Move method of the File class, from the same System.IO namespace.

The following files are used in the example above. The file name is on the left and its description is on the right:

Group of FilesInput DocumentType
Supported file formats

Test File (Doc).doc

Microsoft Word 95/6.0 or Microsoft Word 97 – 2003 document.

 Test File (Dot).dotMicrosoft Word 95/6.0 or Microsoft Word 97 – 2003 template.

Test File (Docx).docx

Office Open XML WordprocessingML document without macros.


Test File (Docm).docm

Office Open XML WordprocessingML document with macros.

 Test File (Dotx).dotxOffice Open XML WordprocessingML template.
 Test File (Dotm).dotmOffice Open XML WordprocessingML template with macros.
 Test File (XML).xmlFlatOPC OOXML Document.

Test File (RTF).rtf

Rich Text Format document.

 Test File (WordML).xmlMicrosoft Word 2003 WordprocessingML document.
 Test File (HTML).htmlHTML document.
 Test File (MHTML).mhtmlMHTML (Web archive) document.
 Test File (Odt).odtOpenDocument Text (OpenOffice Writer).
 Test File (Ott).ottOpenDocument Document Template.

Test File (DocPreWord60).doc

Microsoft Word 2.0 document.

Encrypted documents

Test File (Enc).doc

Encrypted Microsoft Word 95/6.0 or Microsoft Word 97 – 2003 document.


Test File (Enc).docx

Encrypted Office Open XML WordprocessingML document.

Unsupported file formats

Test File (JPG).jpg

JPEG image file.

  • No labels