Unicode C

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.

Unicode C

#include <C_CkGzipW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkGzipW gzip;
    const wchar_t *inputFile;
    const wchar_t *outputFile;

    success = FALSE;

    //  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.

    gzip = CkGzipW_Create();

    //  Set custom Gzip properties:
    CkGzipW_putComment(gzip,L"Example Gzip file created with Chilkat");
    CkGzipW_putFilename(gzip,L"custom_name.txt");
    CkGzipW_putCompressionLevel(gzip,9);
    CkGzipW_putLastModStr(gzip,L"Wed, 1 Apr 2025 12:45:26 -0500");

    //  The file to be compressed:
    inputFile = L"example.txt";
    outputFile = L"example.txt.gz";

    //  Compress the file:
    success = CkGzipW_CompressFile(gzip,inputFile,outputFile);
    if (success == FALSE) {
        wprintf(L"%s\n",CkGzipW_lastErrorText(gzip));
        CkGzipW_Dispose(gzip);
        return;
    }

    wprintf(L"Compression successful.\n");
    wprintf(L"Gzip file created: %s\n",outputFile);


    CkGzipW_Dispose(gzip);

    }