DataFlex

Compress a File to Gzip with Custom Metadata

See more Gzip Examples

This example demonstrates how to use the CompressFile method to create a Gzip (.gz) file while customizing the metadata embedded in the Gzip header.

Before compression, several properties are set:

• Comment: Adds a descriptive comment to the Gzip file.
• Filename: Specifies the filename to embed in the Gzip data, which may be used by extraction tools as the default output name.
• CompressionLevel: Controls the tradeoff between compression ratio and speed (set to maximum in this example).
• LastModStr: Sets the last-modified timestamp using an RFC 822 formatted date string.

After setting these properties, the input file is compressed and written to a .gz file. This approach allows you to embed meaningful metadata along with the compressed data.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoGzip
    String sInputFile
    String sOutputFile
    String sTemp1

    Move False To iSuccess

    // This example demonstrates how to compress a file to Gzip format
    // while setting custom metadata such as comment, filename,
    // compression level, and last-modified date.

    Get Create (RefClass(cComChilkatGzip)) To hoGzip
    If (Not(IsComObjectCreated(hoGzip))) Begin
        Send CreateComObject of hoGzip
    End

    // Set custom Gzip properties:
    Set ComComment Of hoGzip To "Example Gzip file created with Chilkat"
    Set ComFilename Of hoGzip To "custom_name.txt"
    Set ComCompressionLevel Of hoGzip To 9
    Set ComLastModStr Of hoGzip To "Wed, 1 Apr 2025 12:45:26 -0500"

    // The file to be compressed:
    Move "example.txt" To sInputFile
    Move "example.txt.gz" To sOutputFile

    // Compress the file:
    Get ComCompressFile Of hoGzip sInputFile sOutputFile To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoGzip To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Compression successful."
    Showln "Gzip file created: " sOutputFile


End_Procedure