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.

C

#include <C_CkGzip.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkGzip gzip;
    const char *inputFile;
    const char *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 = CkGzip_Create();

    //  Set custom Gzip properties:
    CkGzip_putComment(gzip,"Example Gzip file created with Chilkat");
    CkGzip_putFilename(gzip,"custom_name.txt");
    CkGzip_putCompressionLevel(gzip,9);
    CkGzip_putLastModStr(gzip,"Wed, 1 Apr 2025 12:45:26 -0500");

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

    //  Compress the file:
    success = CkGzip_CompressFile(gzip,inputFile,outputFile);
    if (success == FALSE) {
        printf("%s\n",CkGzip_lastErrorText(gzip));
        CkGzip_Dispose(gzip);
        return;
    }

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


    CkGzip_Dispose(gzip);

    }