Visual FoxPro

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.

Visual FoxPro

LOCAL lnSuccess
LOCAL loGzip
LOCAL lcInputFile
LOCAL lcOutputFile

lnSuccess = 0

* 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.

loGzip = CreateObject('Chilkat.Gzip')

* Set custom Gzip properties:
loGzip.Comment = "Example Gzip file created with Chilkat"
loGzip.Filename = "custom_name.txt"
loGzip.CompressionLevel = 9
loGzip.LastModStr = "Wed, 1 Apr 2025 12:45:26 -0500"

* The file to be compressed:
lcInputFile = "example.txt"
lcOutputFile = "example.txt.gz"

* Compress the file:
lnSuccess = loGzip.CompressFile(lcInputFile,lcOutputFile)
IF (lnSuccess = 0) THEN
    ? loGzip.LastErrorText
    RELEASE loGzip
    CANCEL
ENDIF

? "Compression successful."
? "Gzip file created: " + lcOutputFile

RELEASE loGzip